Polysialic acid derivatives, methods of production, and uses in enhancing cancer antigen production and targeting

ABSTRACT

The present invention relates to compositions and methods of their production and use, including use in increasing de-N-acetyl sialic acid antigen of a mammalian cell and methods that exploit the increase in deNAc sialic acid antigen on such cells.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority benefit of U.S. provisional applicationSer. No. 60/958,391, filed Jul. 3, 2007, and to U.S. patent applicationSer. No. 12/167,909, filed on Jul. 3, 2008, which applications areincorporated herein by reference in their entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

This invention was made with government support under grants no. AI64314awarded by the National Institute of Allergy and Infectious Diseases,and the National Institute of Health. The government has certain rightsin this invention.

TECHNICAL FIELD

This disclosure relates to polysialic acid derivatives, compositions,methods of their production and uses.

BACKGROUND

One goal of cancer immunotherapy is to identify antigens that are eitheruniquely expressed on tumor cells and/or are overexpressed (Carter et alEndocrine-Related Cancer, 2004, 11:659). The antigens exhibiting theseproperties can then be used as targets of antibodies elicited byvaccination or monoclonal antibodies and antibody conjugatesadministered therapeutically. Antibodies that are reactive with antigensthat are uniquely expressed or are relatively overexpressed in cancercells can limit growth and/or metastasis of the cells. The mechanismsinclude antibody dependent cellular cytotoxicity (ADCC), antibodydependent cytotoxicity (ADC), or complement-dependent cytotoxicity (CDC)(Carter et al Endocrine-Related Cancer, 2004, 11:659). Further,antibodies that are reactive with cell surface antigens can beinternalized after binding to the cell surface antigen by endocytosis.Thus, attachment of cytotoxic drugs or toxins to the antibody canprovide a means to specifically target the reagents to cancer cells.

Many human tumors have been shown to uniquely express or overexpress aderivative of poly alpha (2→8) N-acetyl neuraminic acid that containsde-N-acetyl residues using a murine monoclonal antibody, SEAM 3 (Moe etal, Infect. Immun., 2005, 73:2123). SEAM 3 binds to poly alpha (2→8)N-acetyl neuraminic acid that contains a mixture of N-acetyl andde-N-acetyl residues. SEAM 3 can be used to detect expression of thisantigen both intracellularly and on the cell surface and has functionalactivity against tumor cells that express the antigen.

Sialic acids are N- and/or O-substituted derivatives of the nine carbonacidic sugar, neuraminic acid (Varki, A. Glycobiology, 1992, 2:25). Inhumans, the sugars are located on the terminal ends of a wide variety ofcell surface glycoproteins and glycolipids and have an important role inmany biological processes. In cancer, cells that can metastasize oftenhave larger amounts of sialic acid-modified glycoproteins, which mayhelp them enter the blood stream. Also, it has long been recognized thatthe sialic acid of tumor cells is modified in ways that differ fromnormal cells (Hakamori Cancer Res. 1996, 56:5309, Dall'Olio Clin. Mol.Pathol. 1996, 49:M126, Kim and Varki Glycoconj. J. 1997, 14:569). Forinstance, altered expression patterns of sialic acid and its derivativeshave been used as markers for abnormal cellular processes such ascancer. (O'Kennedy et al., Cancer Lett., 1991 58:91; Vedralova et al.Cancer Lett. 1994 78:171; and Horgan et al., Clin. Chim. Acta., 1982118:327; and Narayanan, S. Ann. Clin. Lab. Sci. 1994 24:376).

One sialic acid derivative thought to be uncommon in normal cells, butpresent on cancer cells is de-N-acetyl sialic acid (Hanai et al J. Biol.Chem. 1988, 263:6296, Manzi et al J. Biol. Chem. 1990, 265:1309, Sjoberget al J. Biol. Chem. 1995, 270:2921, Chamas et al 1999, Cancer Res.59:1337; and Popa et al Glycobiology. 2007 17:367).

Sialic acid derivatives that are recognized by specific antibodies andthe level of expression of the derivative can be manipulated both invitro and in vivo. Most often, the expression of a particular sialicacid derivative in human cells has been manipulated by providingderivatives of mannosamine (Bertozzi et al., “Chemical Glycobiology”Science (2001) 291:2357-2364). For example, it has been shown thatproviding exogenous N-propionyl mannosamine results in the production ofN-propionyl polysialic acid (N—Pr PSA) derivatives that can be detectedby anti-N—Pr PSA monoclonal antibodies and polyclonal antibodieselicited by immunization with an N—Pr PSA-tetanus toxoid conjugatevaccine (Zou et al J. Biol. Chem., 2004, 279:25390).

It has also been shown that eukaryotic cells can compensate for a blockof internal sialic acid biosynthesis by acquiring another precursor ofsialic acid biosynthesis, N-acetyl neuraminic acid, from extracellularsources (Oetke et al, Eur. J. Biochem., 2001, 268:4553). Cells also canacquire sialic acid derivatives, such as N-glycoyl sialic acid, fromN-glycoyl sialic acid-containing glycoconjugates by pinocytosis (Bardoret al, J. Biol. Chem., 2006, 280:4228). It has been suggested that thesialic acid present on internalized glycoconjugates is hydrolyzed toN-acyl neuraminic acid when endocytotic vesicles fuse with lysozomes.The free N-acyl neuraminic acid is then transported first to thecytoplasm then to the nucleus by specific transport proteins where it isfinally converted to the sialic acid transferase substrate, CMP-N-acylneuraminic acid (Bardor et al, J. Biol. Chem., 2006, 280:4228).

Literature

Amino sugars, derivatives and related literature of interest arereported in the following U.S. Pat. Nos. 4,021,542; 4,062,950;4,175,123; 4,216,208; 4,254,256; 4,314,999; 4,656,159; 4,713,374;4,797,477; 4,803,303; 4,840,941; 4,914,195; 4,968,786; 4,983,725;5,231,177; 5,243,035; 5,264,424; 5,272,138; 5,332,756; 5,667,285;5,674,988; 5,759,823; 5,962,434; 6,075,134; 6,110,897; 6,274,568;6,407,072; 6,458,937; 6,548,476; 6,697,251; 6,680,054; 6,936,701; and7,070,801, and in the following references: Angata and Varki Chem. Rev.2002, 102:439; Hakamori Cancer Res. 1996, 56:5309; Dall'Olio Clin. Mol.Pathol. 1996, 49:M126; Kim and Varki Glycoconj. J. 1997, 14:569; Hanaiet al J. Biol. Chem. 1988, 263:6296; Manzi et al J. Biol. Chem. 1990,265:1309; Sjoberg et al J. Biol. Chem. 1995, 270:2921; Chamas et alCancer Res. 1999, 59:1337; Popa et al Glycobiology. 2007 17:367; Kayseret al J. Biol. Chem. 1992 267:16934; Keppler et al Glycobiology 2001,11:11R; Luchansky et al Meth. Enzymol. 2003, 362:249; Oetke et al Eur.J. Biochem. 2001, 268:4553; Collins et al Glycobiology 2000, 10:11; andBardor et al J. Biol. Chem. 2005, 280:4228.

The antibody SEAM 3 is reported in Moe et al, Infect. Immun., 2005,73:2123. Sodium borohydride reactions and related are reported invarious references, such as Hirano et al, Connect Tissue Res, 1975,3:73; Shimamura et al, Arch Biochem Biophys, 1984, 232:699; andDjanashvili et al, Chem Eur J, 2005, 11:4010.

Various references report on sialic acid precursors, derivatives,antigens and uses (Zou et al J. Biol. Chem., 2004, 279:25390; Oetke etal Eur. J. Biochem., 2001, 268:4553; Bardor et al, J. Biol. Chem., 2006,280:4228; Bertozzi et al., “Chemical Glycobiology” Science (2001)291:2357-2364). See also US 2007/0010482; U.S. application Ser. No.11/645,255, filed Dec. 22, 2006; WO 2006/002402; and PCT applicationserial no. PCT/US2006/04885, filed Dec. 22, 2006.

SUMMARY

The present invention generally relates to compositions and methods oftheir production and use, including use in increasing de-N-acetyl sialicacid antigen of a mammalian cell and methods that exploit the increasein deNAc sialic acid antigen on such cells.

In one embodiment, the methods involve increasing antigen on the surfaceof a mammalian cell, particularly a cancer cell, by contacting the cellwith an effective amount of a composition described herein, which methodcan be exploited to facilitate binding of an antibody to a cell, as wellas to directly reduce the viability of a cell, particularly when appliedat a higher concentrations than is necessary to elicit antibodies to theantigen.

Also provided are methods of eliciting antibodies to a cell in a subjecthaving a deNAc sialic acid antigen by using an immunogenic compositiondisclosed herein.

The compositions disclosed herein include an isolated polysialic acidderivative that comprises a mixture of N-acetyl and de-N-acetyl residuesand that is resistant to degradation by exoneuraminidase. Thesecompositions also include polysialic acid derivatives having anon-reducing end that is enriched with de-N-acetyl residues, as well ascompositions that are enriched with such derivatives. The compositionsfurther include a substantially unoxidized isolated polysialic acidderivative having mixture of N-acetyl sialic acid and de-N-acetyl sialicresidues, and a non-reducing end de-N-acetyl residue resistant todegradation by exoneuraminidase, where the composition is substantiallyfree of polysialic acid having a non-reducing end N-acetyl sialic acidresidue. The compositions also include an aggregate of an isolatedpolysialic acid derivative disclosed herein, including compositionsenriched with an aggregate of polysialic acid derivatives havingvariable chain lengths, as well as compositions of an aggregate of apolysialic acid derivative having a defined degree of polymerization.

Methods for producing the compositions can involve: (i) treating a firstcomposition with exoneuraminidase, where the first composition comprisesa polysialic acid derivative having a mixture of N-acetyl andde-N-acetyl residues; and (ii) isolating from the first compositionpolysialic acid derivatives resistant to degradation by theexoneuraminidase. Another method of production involves: (i) providing afirst composition comprising de-N-acetylated polysialic acid having amixture of N-acetyl and de-N-acetyl residues; (ii) re-acetylating thede-N-acetylated polysialic acid to generate a second compositioncomprising partially re-acetylated polysialic acid; and (iii) isolatingfrom the second composition polysialic acid derivative that is resistantto degradation by exoneuraminidase. Another method of productioninvolves forming an aggregate of an isolated polysialic acid derivativeby exposing the derivative to aggregating conditions to form anaggregate, and isolating the aggregate. An additional method forproducing the compositions involves (i) providing a solution comprisinga mixture of polysialic acid derivatives each having: a different degreeof polymerization, a different mixture of N-acetyl residues andde-N-acetyl residues, and a non-reducing end N-acetyl sialic acidresidue; (ii) subjecting the solution to ion exchange chromatography togenerate fractions; and (iii) isolating from one or more of thefractions a polysialic acid derivative having a defined degree ofpolymerization and a non-reducing end de-N-acetyl residue resistant todegradation by exoneuraminidase.

The compositions and methods disclosed herein take advantage of thefinding that the polysialic acid derivatives disclosed herein arecapable of being exogenously applied to cells, and then taken up andpresented on a cell surface as a substantially intact antigen that isobserved on tumor cells but not on normal cells. This property extendsfrom the finding that the compositions of the present disclosure areunexpectedly stable to degradation when applied exogenously to a cell oradministered to a subject.

The compositions and methods disclosed herein can also take advantage ofthe finding that the amount of intact antigen on the cell surface isgreatly increased relative to prior polysialic acid compositions thatare susceptible to degradation by exoneuraminidase and/or deficient in anon-reducing end enriched for de-N-acetyl residues. The compositions andmethods disclosed herein can also take advantage of the finding that theincreased amount of antigen presented by the cells provides not only anovel target for antibodies to bind with great specificity andselectively, but can increase the immune response in a subject directedagainst cells that express the antigen relative to prior polysialic acidcompositions that are susceptible to degradation by exoneuraminidaseand/or deficient in a non-reducing end enriched for de-N-acetylresidues. The compositions and methods disclosed herein can also takeadvantage of the finding that aggregates of the polysialic acidderivatives are more readily taken up by cells and expressed on the cellsurface compared to the corresponding non-aggregated derivative. Thecompositions and methods disclosed herein can also take advantage of thefinding that substantially unoxidized and purified polysialic acidderivatives can be produced and characterized, and that smallerderivatives exhibit as much activity as longer derivatives, indicatingthe smallest derivatives contain the minimal features necessary foreffective activity.

As such, the methods and compositions of the present disclosure find usein many applications, including in the treatment and/or prevention ofbacterial infections and cancer.

Accordingly, in one aspect the present disclosure provides methods ofincreasing a de-N-acetylated antigen of a cancer cell comprisingcontacting a cancer cell having a de-N-acetyl sialic acid antigen withan effective amount of a composition comprising a polysialic acidderivative to increase the amount of the de-N-acetyl sialic acid antigenof said cell, wherein said polysialic acid derivative is substantiallyunoxidized and purified and comprises (i) a mixture of N-acetyl sialicacid and de-N-acetyl sialic acid residues, and (ii) a non-reducing endde-N-acetyl sialic acid residue that is resistant to degradation byexoneuraminidase.

In related embodiments, the cancer cell presents a de-N-acetyl sialicacid epitope and, in some embodiments, is a neuroblastoma cell, aleukemia cell, or a melanoma cell. In further related embodiments, theantigen comprises a de-N-acetyl sialic acid epitope. In relatedembodiments the cell is in a subject, and said contacting comprisesadministering to said subject an effective amount of said composition.In related embodiments administering is by infusion or by localinjection. Administering can be prior to surgical intervention to removecancerous cells, at the time of or after surgical intervention to removecancerous cells, and/or with at least one of an immunotherapy, a cancerchemotherapy or a radiation therapy to the subject.

In another aspect, the present disclosure provides methods offacilitating binding of an antibody to a cell having a de-N-acetylsialic acid antigen comprising contacting a cell having a de-N-acetylsialic acid antigen with an effective amount of a composition comprisinga polysialic acid derivative so as to increase the amount of saidantigen on said cell, wherein said polysialic acid derivative issubstantially unoxidized and purified and comprises (i) a mixture ofN-acetyl sialic acid and de-N-acetyl sialic acid residues, and (ii) anon-reducing end de-N-acetyl sialic acid residue that is resistant todegradation by exoneuraminidase; and contacting said cell with anantibody specific for said antigen to facilitate binding of saidantibody to said cell. In related embodiments, binding of the antibodyto the cell facilitates uptake of said antibody by said cell. In relatedembodiments, the antigen comprises a de-N-acetylated sialic acidepitope. In some embodiments, binding of the antibody to said cell iscytotoxic to the cell. The antibody can be specific for ade-N-acetylated sialic acid epitope of said antigen, and in specificembodiments is the SEAM 3 monoclonal antibody.

In related embodiments, the cell is a cancer cell. In relatedembodiments, the antigen is extracellularly accessible cell during celldivision. In further embodiments, the antibody can be provided asconjugate, e.g., where the conjugate comprises a detectable label or acytotoxic drug (e.g., a toxin

In another aspect the present disclosure provides methods of elicitingantibody to a cell having a de-N-acetyl sialic acid antigen in asubject, comprising administering to a subject an effective amount of animmunogenic composition comprising an antigen so as to increaseexpression of said antigen by said cell, wherein said antigen comprisesa substantially unoxidized and purified polysialic acid derivativehaving (i) a mixture of N-acetyl sialic acid and de-N-acetyl sialic acidresidues, and (ii) a non-reducing end de-N-acetyl sialic acid residuewhich is resistant to degradation by exoneuraminidase, and wherein saidadministering is effective to elicit production of an antibody in saidsubject that specifically binds said cell. In related embodiments,binding of the antibody to the cell is cytotoxic. In further relatedembodiments, the antibody is specific for a de-N-acetylated sialic acidepitope. In related embodiments, the cell is a cancer cell. In relatedembodiments, antigen is extracellularly accessible during cell division.

In another aspect, the present disclosure provides methods of reducingthe viability of a cancer cell comprising contacting a cancer cell withan effective amount of a composition comprising a polysialic acidderivative so as to reduce the viability of said cell, wherein saidpolysialic acid derivative has a reducing end and a non-reducing end,and wherein said polysialic acid derivative is a substantiallyunoxidized and purified oligosaccharide comprising (i) a mixture ofN-acetyl sialic acid and de-N-acetyl sialic acid residues, and (ii) ade-N-acetyl sialic acid residue at said non-reducing end that isresistant to degradation by exoneuraminidase. In related embodiments,intracellular uptake of the polysialic acid derivative is cytotoxic tothe cancer cell. In related embodiments, the cancer cell is aneuroblastoma cell, a leukemia cell, or a melanoma cell.

In related embodiments, the polysialic derivative comprises at least onedimer of de-N-acetyl sialic acid and N-acetyl sialic acid linked througha glycosidic bond selected from α(2→8) and α(2→9), where the polysialicderivative can have a degree of polymerization of from about 2-10, fromabout 2-5, of about 2-4, and/or of about 2. In further relatedembodiments, the mixture comprises de-N-acetyl sialic residues in anamount of about 10%-60%. In related embodiments, the polysialicderivative has about 1 de-N-acetyl sialic residue per polysialic acidderivative chain. The polysialic acid derivative can comprise aconjugate in related embodiments. In further related embodiments, thenon-reducing end de-N-acetyl sialic acid is linked through a glycosidicbond to an adjacent N-acetyl sialic acid so as to form a de-N-acetylsialic acid antigen at the non-reducing end of said polysialic acidderivative. In related embodiments, the de-N-acetyl sialic acid isneuraminic acid, and the N-acetyl sialic acid is N-acetyl neuraminicacid. In related embodiments, at least one of the neuraminic acid andsaid N-acetyl neuraminic acid comprises at least one O-acetylated group.In further related embodiments, the polysialic acid is obtainable from acapsular polysaccharide homopolymer of a bacterium selected from thegroup consisting of Escherichia coli K1, Neisseria meningitidisSerogroup B, and Neisseria meningitidis Serogroup C. In relatedembodiments, the cell is in a subject, and said contacting comprisesadministering to said subject an effective amount of said composition.

In another aspect, the present disclosure provides methods of producingan isolated polysialic acid derivative having a defined degree ofpolymerization and a non-reducing end de-N-acetyl residue resistant todegradation by exoneuraminidase comprising providing a solutioncomprising a mixture of polysialic acid derivatives each having (i) adifferent degree of polymerization, (ii) a different mixture of N-acetylresidues and de-N-acetyl residues, and (iii) a non-reducing end N-acetylsialic acid residue; subjecting said solution to ion exchangechromatography to generate fractions; and isolating from one or more ofsaid fractions a polysialic acid derivative having a defined degree ofpolymerization and a non-reducing end de-N-acetyl residue resistant todegradation by exoneuraminidase, whereby said isolated polysialic acidderivative is produced. In related embodiments, the ion exchangechromatography is anion exchange chromatography. In related embodiments,the isolated polysialic acid derivative has a degree of polymerizationof about 2 to 10, of about 2 to 5, about 2-4, and/or about 2. In relatedembodiments, the isolated polysialic acid derivative is substantiallyunoxidized.

In related embodiments, the non-reducing end de-N-acetyl sialic acidresidue of said isolated polysialic acid derivative is linked through aglycosidic bond to an N-acetyl sialic acid residue. In relatedembodiments, the glycosidic bond is selected from the group consistingof α(2→8) and α(2→9). In further related embodiments, the mixturecomprises de-N-acetyl sialic residues in an amount of about 10%-60%. Inrelated embodiments, the isolated polysialic derivative has about 1de-N-acetyl sialic residue per polysialic acid derivative chain. Inother related embodiments, the isolated polysialic acid derivativecomprises a conjugate.

In other related embodiments, the de-N-acetyl sialic acid is neuraminicacid, and said N-acetyl sialic acid is N-acetyl neuraminic acid. Inrelated embodiments, at least one of the neuraminic acid and theN-acetyl neuraminic acid comprises at least one O-acetylated group. Inrelated embodiments, the polysialic acid derivative is derivable from acapsular polysaccharide homopolymer of a bacterium selected from thegroup consisting of Escherichia coli K1, Neisseria meningitidisSerogroup B, and Neisseria meningitidis Serogroup C. In relatedembodiments, the mixture of polysialic acid derivatives is produced bytreating a first composition comprising a polysialic acid derivativehaving a mixture of N-acetyl and de-N-acetyl residues withexoneuraminidase. In further related embodiments, the mixture ofpolysialic acid derivatives is produced by re-acetylating a firstcomposition comprising de-N-acetylated polysialic acid to generate asecond composition comprising partially re-acetylated polysialic acidhaving a mixture of N-acetyl and de-N-acetyl residues and which isresistant to degradation by exoneuraminidase.

In another aspect, the present disclosure provides isolated polysialicacid derivatives produced according to the methods disclosed herein, aswell as pharmaceutical compositions comprising such isolated polysialicacid derivatives.

In another aspect, the present disclosure provides compositionscomprising an isolated polysialic acid derivative, said isolatedpolysialic acid derivative being substantially unoxidized and comprising(i) mixture of N-acetyl sialic acid and de-N-acetyl sialic residues, and(ii) a non-reducing end de-N-acetyl residue that is resistant todegradation by exoneuraminidase, wherein said composition issubstantially free of polysialic acid having a non-reducing end N-acetylsialic acid residue. In related embodiments, the isolated polysialicderivative comprises at least one dimer of de-N-acetyl sialic acid andN-acetyl sialic acid linked through a glycosidic bond selected fromα(2→8) and α(2→9). In related embodiments, the isolated polysialicderivative has a degree of polymerization of about 2-10, of about 2-5,about 2-4, and/or about 2. In related embodiments, the non-reducing endde-N-acetyl sialic acid residue is linked through a glycosidic bond toan N-acetyl sialic acid residue. In related embodiments, the mixturecomprises de-N-acetyl sialic residues in an amount of about 10%-60%. Infurther related embodiments, the isolated polysialic derivative hasabout 1 de-N-acetyl sialic residue per polysialic acid derivative chain.In other embodiments, the isolated polysialic acid derivative comprisesa conjugate. In certain embodiments, the de-N-acetyl sialic acid isneuraminic acid, and said N-acetyl sialic acid is N-acetyl neuraminicacid, and can be such that at least one of said neuraminic acid and saidN-acetyl neuraminic acid comprises at least one O-acetylated group. Inrelated embodiments, the isolated polysialic acid derivative isderivable from a capsular polysaccharide homopolymer of a bacteriumselected from the group consisting of Escherichia coli K1, Neisseriameningitidis Serogroup B, and Neisseria meningitidis Serogroup C. Incertain embodiments, the composition comprises an aggregate of thepolysialic acid derivative, where the aggregate can comprise amicroscopic particle.

In another aspect, the present disclosure provides methods of producingan aggregate comprising a polysialic acid derivative comprising placinga substantially unoxidized and purified polysialic acid derivative underaggregating conditions so as to form an aggregate, said polysialic acidderivative comprising (i) a mixture of N-acetyl and de-N-acetylresidues, said de-N-acetyl residues comprising about 10%-80% of saidmixture, and (ii) a non-reducing end resistant to degradation byexoneuraminidase. In related embodiments, the aggregating condition isheating (e.g., heating is from about 30° C. to 70° C.) or the additionof an aggregating excipient (e.g., aluminum hydroxide). In relatedembodiments, the aggregate is a particle, e.g., a microscopic particle.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows flow cytometry results for an irrelevant, isotype-matchedcontrol mAb IgG2b and SEAM 3 binding to CHP-134 neuroblastoma cellsexogenously exposed to a polysialic acid (colominic acid), are-N-acetylated polysialic acid derivative (re-N-acetylated colominicacid (ReAc)), and a polysialic acid derivative that is resistant toexoneuraminidase (re-N-acetylated colominic acid that has been selectedfor resistance to exoneuraminidase (ReAcSia)).

FIG. 2 shows flow cytometry results for an irrelevant, isotype-matchedcontrol mAb IgG2b and SEAM 3 binding to Jurkat leukemia cellsexogenously exposed to a polysialic acid (colominic acid), are-N-acetylated polysialic acid derivative (re-N-acetylated colominicacid (ReAc)), and a polysialic acid derivative that is resistant toexoneuraminidase (re-N-acetylated colominic acid that has been selectedfor resistance to exoneuraminidase (ReAcSia)).

FIG. 3 shows flow cytometry results for an irrelevant, isotype-matchedcontrol mAb IgG2b and SEAM 3 binding to SK-MEL 28 melanoma cellsexogenously exposed to a polysialic acid (colominic acid),re-N-acetylated polysialic acid derivative (re-N-acetylated colominicacid (ReAc)), and a polysialic acid derivative that is resistant toexoneuraminidase (re-N-acetylated colominic acid that has been selectedfor resistance to exoneuraminidase (ReAcSia)).

FIG. 4 shows results in histogram format for an irrelevant,isotype-matched control mAb IgG2b and SEAM 3 binding (FIG. 4, Panel A)and total fluorescence of cells (FIG. 4, Panel B) for Jurkat, SK-MEL 28melanoma and CHP-134 neuroblastoma cells exogenously exposed to noderivative (None), a polysialic acid (colominic acid (Col)), are-N-acetylated polysialic acid derivative (re-N-acetylated colominicacid (ReAc)), and a polysialic acid derivative that is resistant toexoneuraminidase (re-N-acetylated colominic acid that has been selectedfor resistance to exoneuraminidase (ReAcSia)).

FIG. 5 shows the fluorescence on the cell surface (indicated y redstaining, represented in the gray scale figure by light gray surroundinga darkly stained nucleus), as measured by confocal microscopy, resultingfrom SEAM 3 binding to SK-MEL-28 melanoma cells exogenously exposed to apolysialic acid derivative (FIG. 5, Panels A and C, colominic acid) orto a polysialic acid derivative that is resistant to exoneuraminidase(FIG. 5, Panels B and D, re-N-acetylated colominic acid that has beenselected for resistance to exoneuraminidase ReAcSia) in the absence(FIG. 5, Panels A and B) or presence (FIG. 5, Panels C and D) of TritonX-100.

FIG. 6 is a Western blot detecting the presence of mouse immunoglobulinlight chains in soluble SK-MEL 28 melanoma cytosolic cell proteinsseparated on a SDS-PAGE gel after culturing the cells for 48 hrs in thepresence of SEAM 3 or control mAbs.

FIG. 7 shows HPAC-PAD chromatograms of colominc acid 0, 1, 2, and 6hours of alkaline hydrolysis.

FIG. 8 contains bar graphs showing the effect on SEAM 3 binding toJurkat cells after contacting the cells with colominic acid derivativesproduced by alkaline hydrolysis for 1, 2, or 6 hours (panel A) or 10,20, 40, or 60 minutes compared to the ReAcSia derivative (panel B).

FIG. 9 shows the effect of the 40 min DeNAc col derivative concentrationon the viability of Jurkat cells after 40 hours incubation.

FIG. 10 shows the AEC chromatogram of acid hydrolyzed 40 min DeNAc colderivatives. The letters indicate fractions that were pooled.

FIG. 11 shows HPAC-PAD chromatograms of selected individual fractions(microtiter plate well indicated above each chromatogram) from the AECpurification of acid hydrolyzed 40 min DeNAc col. The degree ofpolymerization (Dp) of oliogmers 2 through 10 are indicated below thechromatogram of the unpurified derivatives.

FIG. 12 shows the HPAC-PAD chromatograms of the fractions that werepooled as indicated in FIG. 10. After pooling, dialysis, andlyophilization, smaller oliogmers that were not present in the originalfractions are present indicating that the longer oliomers hydrolyze toproduce shorter oliogmers.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

The present disclosure is based on the discovery that a de-N-acetylatedsialic acid cancer cell antigen can be greatly increased in cancer cellsby externally providing a synthetic neuraminic acid-containingpolysialic acid (PSA) that is resistant to degradation byexoneuraminidase and that has been enriched for neuraminic acidresidues. The antigen, a poly alpha (2→8) or alpha (2→9) N-acetylneuraminic acid (PSA), contains a mixture of N-acetyl and de-N-acetylresidues (that is, neuraminic acid-containing PSA). Rather than beinghydrolyzed to monomers by the cells, it appears that the neuraminicacid-containing PSA derivatives are taken up by cells and transferred asan intact polymeric molecule to produce a surface expressedglycoconjugate. There is no known mechanism for this to occur in humancells. The antigen also accumulates in the nucleoli of cells to asignificant degree. Regardless of mechanism, the PSA derivatives aretaken up by the cells and processed in a manner so as to render the cellless viable and present a de-N-acetyl sialic acid antigen on the cellsurface. The disclosure also is based on the discovery that aggregatesof the neuraminic acid-containing PSA derivatives are more readily takenup by cells and expressed on the cell surface as compared to thecorresponding non-aggregated derivative. Further, the disclosure isbased on the discovery that internalization by cells of an antibody,SEAM 3, that recognizes the neuraminic acid-containing PSA epitope isgreatly increased by the increased surface expressed neuraminicacid-containing PSA antigen resulting from externally providing thesynthesized antigen. The disclosure is also based on the discovery thatshorter chain length PSA derivatives which are substantially unoxidizedand purified, and which possess a non-reducing end de-N-acetyl residue,are significantly more active than corresponding PSA derivatives lackingsuch features. The disclosure is further based on such PSA derivativesand methods of their production.

Thus, the discovery provides compositions and methods for increasing theexpression of a sialic acid antigen that is observed on cancer cells butnot on normal cells. This can be useful to render these cells moreimmunogenic, reduce viability of the cells in general, and/or tofacilitate binding of antibodies specific for a de-N-acetyl sialic acidantigen.

Before the present invention and specific exemplary embodiments of theinvention are described, it is to be understood that this invention isnot limited to particular embodiments described, as such may, of course,vary. It is also to be understood that the terminology used herein isfor the purpose of describing particular embodiments only, and is notintended to be limiting, since the scope of the present invention willbe limited only by the appended claims.

Where a range of values is provided, it is understood that eachintervening value, to the tenth of the unit of the lower limit unlessthe context clearly dictates otherwise, between the upper and lowerlimit of that range and any other stated or intervening value in thatstated range is encompassed within the invention. The upper and lowerlimits of these smaller ranges may independently be included in thesmaller ranges is also encompassed within the invention, subject to anyspecifically excluded limit in the stated range. Where the stated rangeincludes one or both of the limits, ranges excluding either both ofthose included limits are also included in the invention.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. Although any methods andmaterials similar or equivalent to those described herein can also beused in the practice or testing of the present invention, exemplarymethods and materials are now described. All publications mentionedherein are incorporated herein by reference to disclose and describe themethods and/or materials in connection with which the publications arecited.

It must be noted that as used herein and in the appended claims, thesingular forms “a”, “and”, and “the” include plural referents unless thecontext clearly dictates otherwise. Thus, for example, reference to “anantigen” includes a plurality of such antigens and reference to “thepeptide” includes reference to one or more peptides and equivalentsthereof known to those skilled in the art, and so forth.

The publications discussed herein are provided solely for theirdisclosure prior to the filing date of the present application. Nothingherein is to be construed as an admission that the present invention isnot entitled to antedate such publication by virtue of prior invention.Further, the dates of publication provided may be different from theactual publication dates which may need to be independently confirmed.

DEFINITIONS

When describing the compositions, pharmaceutical formulations containingsuch, and methods of producing and using such compositions, thefollowing terms have the following meanings unless otherwise indicated.It should also be understood that any of the moieties defined forthbelow may be substituted with a variety of substituents, and that therespective definitions are intended to include such substituted moietieswithin their scope.

The term “amino sugar” refers to a sugar or saccharide that contains anamino group in place of a hydroxyl group. Derivatives of aminocontaining sugars, such as N-acetyl-glucosamine, N-acetyl mannosamine,N-acetyl galactosamine, N-acetyl neuraminic acid and sialic acids ingeneral are examples of amino sugars.

The term “analog” or “analogue” refers to without limitation anycompound which has structural similarity to the compounds of the presentdisclosure and would be expected, by one skilled in the art, to exhibitthe same or similar utility as the claimed and/or referenced compounds.

The term “carrier” as used in the context of a carrier conjugated to apolysialic acid derivative generally refers to a peptide or proteincarrier, such as an antibody or antibody fragment. “Carrier” encompassespeptides or proteins that enhance immunogenicity of a compound.

The term “cell surface antigen” (or “cell surface epitope”) refers to anantigen (or epitope) on surface of a cell that is extracellularlyaccessible at any cell cycle stage of the cell, including antigens thatare predominantly or only extracellularly accessible during celldivision. “Extracellularly accessible” in this context refers to anantigen that can be bound by an antibody provided outside the cellwithout need for permeabilization of the cell membrane.

The term “chemotherapy” as used herein refers to use of an agent (e.g.,drug, antibody, etc.), particularly an agent(s) that is selectivelydestructive to a cancerous cell, in treatment of a disease, withtreatment of cancer being of particular interest.

The term “conjugated” generally refers to a chemical linkage, eithercovalent or non-covalent, usually covalent, that proximally associatesone molecule of interest with second molecule of interest.

The term “de-N-acetyl sialic acid antigen” (which may also be referredto as “de-N-acetylated sialic acid antigen” or “deNAc SA antigen”)refers to a compound having or mimicking a deNAc sialic acid epitope(deNAc SA epitope), which epitope is minimally defined by a dimer ofresidues of sialic acid or sialic acid derivative, where the dimercontains at least one de-N-acetylated sialic acid residue adjacent anN-acylated (e.g., acetylated or propionylated) sialic acid residue or asialic acid derivative residue. Examples of de-N-acetyl sialic acidantigens are provided in the present disclosure, and include, withoutlimitation, de-N-acetylated polysaccharide derivatives (“PSderivatives”), de-N-acetylated gangliosides, and de-N-acetylatedderivatives of a sialic-acid modified protein, particularly asialic-acid modified protein that is accessible at an extracellularsurface of a mammalian cell, particularly a human cell, moreparticularly a cancer cell, particularly a human cancer cell. deNAc SAepitopes are also present in polysaccharide capsules of Neisseria,especially N. meningitidis, particularly N. meningitidis Groups B and C,and E. coli K1. It should be noted that description of a deNAc SAantigen as a derivative of a starting molecule (e.g., PS derivative organglioside derivative) is not meant to be limiting as to the method ofproduction of the de-N-acetyl sialic acid antigen, but rather is meantas a convenient way to describe the structure of the exemplary deNAc SAantigen.

The term “derivative” refers to without limitation any compound whichhas a structure derived from the structure of the compounds of thepresent disclosure and whose structure is sufficiently similar to thosedisclosed herein and based upon that similarity, would be expected, byone skilled in the art, to exhibit the same or similar activities andutilities as the claimed and/or referenced compounds.

The term “effective amount” of a compound as provided herein is intendedto mean a non-lethal but sufficient amount of the compound to providethe desired utility. For instance, for eliciting an immune response in asubject to generate anti-deNAc SA antibodies, the effective amount isthe amount which elicits a useful antibody response, e.g., so as toprovide for production of antibodies that can be subsequently isolated(e.g., as in monoclonal antibody production) or to provide for aclinically meaningful immune response in a subject against a bacteria(e.g., as in the context of prophylactic or therapeutic immunizationagainst a disease caused by Neisseria or E. coli K1) or by a cancercharacterized by a deNAc SA epitope. For imparting a reduction inviability of a target cell in general, the effective amount is theamount which reduces viability or killing of the cell or provides for aclinically meaningful reduction in viable target cells in a subject,regardless of mechanism. As will be pointed out below, the exact amountrequired will vary from subject to subject, depending on the species,age, and general condition of the subject, the severity of the conditionor disease that is being treated, the particular compound used, its modeof administration, and the like. Thus, it is not possible to specify anexact “effective amount.” However, an appropriate effective amount maybe determined by one of ordinary skill in the art using only routineexperimentation.

The term “enriched” as used herein refers to a compound or compositionthat has an increase in the proportion of a desirable property orelement. For example, an alpha (2→8) oligosialic acid derivative that is“enriched” for de-N-acetylation at a non-reducing end is an alpha (2→8)oligosialic acid derivative in which the de-N-acetylated residues areprimarily present, including only present, at a non-reducing end,including the non-reducing terminal end. A composition is “enriched” foralpha (2→8) oligosialic acid derivatives having de-N-acetylatednon-reducing ends where the majority of alpha (2→8) oligosialic acidderivatives in the composition (e.g., more than 50%, 55%, 60%, 65%, 70%,75%, 80%, 85%, 90%, 95% or more up to 100%) have a de-N-acetylatedresidue at a non-reducing end, particularly at a non-reducing terminalend.

The term “immunotherapy” refers to treatment of disease (e.g., Neisseriaor E. coli K1 bacterial infection, cancer) by modulating an immuneresponse to a disease antigen. In the context of the presentapplication, immunotherapy refers to providing an antibacterial and/oranti-cancer immune response in a subject by administration of anantibody (e.g., a monoclonal antibody) and/or by administration of anantigen the elicits an anti-tumor antigen immune response in thesubject.

The term “inactivation” of a cell is used herein to indicate that thecell has been rendered incapable of cell division to form progeny. Thecell may nonetheless be capable of response to stimulus and/orbiosynthesis for a period of time, e.g., to provide for production of acell surface molecule (e.g., cell surface protein or polysaccharide).

The term “in combination with” as used herein refers to uses where, forexample, a first therapy is administered during the entire course ofadministration of a second therapy; where the first therapy isadministered for a period of time that is overlapping with theadministration of the second therapy, e.g. where administration of thefirst therapy begins before the administration of the second therapy andthe administration of the first therapy ends before the administrationof the second therapy ends; where the administration of the secondtherapy begins before the administration of the first therapy and theadministration of the second therapy ends before the administration ofthe first therapy ends; where the administration of the first therapybegins before administration of the second therapy begins and theadministration of the second therapy ends before the administration ofthe first therapy ends; where the administration of the second therapybegins before administration of the first therapy begins and theadministration of the first therapy ends before the administration ofthe second therapy ends. As such, “in combination” can also refer toregimen involving administration of two or more therapies. “Incombination with” as used herein also refers to administration of two ormore therapies which may be administered in the same or differentformulations, by the same or different routes, and in the same ordifferent dosage form type.

The term “isolated” is intended to mean that a compound is separatedfrom all or some of the components that accompany it in nature.“Isolated” also refers to the state of a compound separated from all orsome of the components that accompany it during manufacture (e.g.,chemical synthesis, recombinant expression, culture medium, and thelike).

The term “monoclonal antibody” refers to an antibody composition havinga homogeneous antibody population. The term is not limited by the mannerin which it is made. The term encompasses whole immunoglobulinmolecules, as well as Fab molecules, F(ab′)2 fragments, Fv fragments,single chain fragment variable displayed on phage (scFv), fusionproteins comprising an antigen-binding portion of an antibody and anon-antibody protein, and other molecules that exhibit immunologicalbinding properties of the parent monoclonal antibody molecule. Methodsof making polyclonal and monoclonal antibodies are known in the art anddescribed more fully below.

The term “non-reducing end” of an oligo or polysaccharide chain isintended the end portion of the chain bearing the non-reducing glycosylresidue.

The term “reducing end” of an oligo or polysaccharide chain is intendedthe end portion of the chain bearing the reducing glycose residue. Thisis the end of the chain which can be in equilibrium with the open chainaldehyde or ketone form of the saccharide.

The term “pharmaceutically acceptable” refers to a material that is notbiologically or otherwise undesirable, i.e., the material is of amedically acceptable quality and composition that may be administered toan individual along with the selected active pharmaceutical ingredientwithout causing any undesirable biological effects or interacting in adeleterious manner with any of the other components of thepharmaceutical composition in which it is contained.

The term “pharmaceutically acceptable excipient” as used herein refersto any suitable substance which provides a pharmaceutically acceptablevehicle for administration of a compound(s) of interest to a subject.“Pharmaceutically acceptable excipient” can encompass substancesreferred to as pharmaceutically acceptable diluents, pharmaceuticallyacceptable additives and pharmaceutically acceptable carriers.

The terms “polypeptide” and “protein”, used interchangeably herein,refer to a polymeric form of amino acids of any length, which caninclude coded and non-coded amino acids, chemically or biochemicallymodified or derivatized amino acids, and polypeptides having modifiedpeptide backbones. The term includes fusion proteins, including, but notlimited to, fusion proteins with a heterologous amino acid sequence,fusions with heterologous and homologous leader sequences, with orwithout N-terminal methionine residues; immunologically tagged proteins;fusion proteins with detectable fusion partners, e.g., fusion proteinsincluding as a fusion partner a fluorescent protein, β-galactosidase,luciferase, etc.; and the like. Polypeptides may be of any size, and theterm “peptide” refers to polypeptides that are 8-50 residues (e.g., 8-20residues) in length.

The term “purified” is intended to mean a compound of interest has beenseparated from components that accompany it in nature and provided in anenriched form. “Purified” also refers to a compound of interestseparated from components that can accompany it during manufacture(e.g., in chemical synthesis, recombinant expression, culture medium,and the like) and provided in an enriched form. Typically, a compound issubstantially pure when it is at least 50% to 60%, by weight, free fromorganic molecules with which it is naturally associated or with which itis associated during manufacture. Generally, the preparation is at least75%, more usually at least 90%, and generally at least 99%, by weight,of the compound of interest. A substantially pure compound can beobtained, for example, by extraction from a natural source (e.g.,bacteria), by chemically synthesizing a compound, or by a combination ofpurification and chemical modification. A substantially pure compoundcan also be obtained by, for example, enriching a sample having acompound that binds an antibody of interest. Purity can be measured byany appropriate method, e.g., chromatography, mass spectroscopy, HPLCanalysis, etc.

The term “SEAM 3-reactive antigen” refers to an antigen having anepitope that is specifically bound by the monoclonal antibody (mAb) SEAM3 (ATCC Deposit No. HB-12170). Exemplary SEAM 3-reactive antigens areprovided in the working examples.

By “degree of polymerization” or Dp is intended the number of repeatunits in an average polymer chain. Chain length can be reported inmonomer units, as molecular weight, or both.

The term “subject” is intended to cover humans, mammals and otheranimals which contain polysialic acid in any fashion. The terms“subject,” “host,” “patient,” and “individual” are used interchangeablyherein to refer to any mammalian subject for whom diagnosis or therapyis desired, particularly humans. Other subjects may include cattle,dogs, cats, guinea pigs, rabbits, rats, mice, horses, and so on.

In the context of cancer therapies and diagnostics described herein,“subject” or “patient” is used interchangeably herein to refer to asubject having, suspected of having, or at risk of developing a tumor,where the cancer is one associated with cancerous cells expressing ade-N-acetyl sialic acid antigen. Samples obtained from such subject arelikewise suitable for use in the methods of the present disclosure.

A “cancer cell” as used herein refers to a cell exhibiting a neoplasticcellular phenotype, which may be characterized by one or more of, forexample, abnormal cell growth, abnormal cellular proliferation, loss ofdensity dependent growth inhibition, anchorage-independent growthpotential, ability to promote tumor growth and/or development in animmuno-compromised non-human animal model, and/or any appropriateindicator of cellular transformation. “Cancer cell” may be usedinterchangeably herein with “tumor cell”, and encompasses cancer cellsof a solid tumor, a semi-solid tumor, a primary tumor, a metastatictumor, and the like.

As used herein, the terms “determining,” “measuring,” and “assessing,”and “assaying” are used interchangeably and include both quantitativeand qualitative determinations.

It is further noted that the claims may be drafted to exclude anyoptional or alternative element. As such, this statement is intended toserve as antecedent basis for use of such exclusive terminology as“solely”, “only” and the like in connection with the recitation of claimelements, or the use of a “negative” limitation.

All publications and patents cited in this specification are hereinincorporated by reference as if each individual publication or patentwere specifically and individually indicated to be incorporated byreference and are incorporated herein by reference to disclose anddescribe the methods and/or materials in connection with which thepublications are cited. The citation of any publication is for itsdisclosure prior to the filing date and should not be construed as anadmission that the present invention is not entitled to antedate suchpublication by virtue of prior invention. Further, the dates ofpublication provided may be different from the actual publication dateswhich may need to be independently confirmed. To the extent a definitionof a term set out in a document incorporated herein by referenceconflicts with the definition of a term explicitly defined herein, thedefinition set out herein controls.

In further describing the invention, the methods are described first ingreater detail, followed by a review of the various specific methods ofproduction, compositions, formulations, kits and the like that may finduse in the methods, as well as a discussion of representativeapplications in which the methods and compositions find use.

Methods of Increasing Antigen on a Cell

As summarized above, the present disclosure provides methods ofincreasing a de-N-acetyl sialic acid antigen on a mammalian cell. Themethods find use in facilitating binding of an antibody to a mammaliancell, eliciting antibodies to a mammalian cell as well as more specificapplications including use in various methods of treating a hostsuffering from disease or condition in need thereof (as described ingreater detail below).

A featured aspect involves use of a polysialic acid derivative of thepresent disclosure in a method for increasing antigen on a cancer cell.This method involves contacting the cancer cell with an effective amountof a composition that includes an antigen so as to increase the amountof the antigen on the cell. The antigen comprises a polysialic acidderivative having a mixture of N-acetyl and de-N-acetyl residues andthat is resistant to degradation by exoneuraminidase (as described ingreater detail below). An antigen of particular interest for use in thismethod is one in which the composition is enriched with polysialic acidderivative having a non-reducing end that is enriched for de-N-acetylresidues. In a specific embodiment, the polysialic acid derivative is anaggregate. The aggregates can be molecular aggregates or microscopicaggregates. Aggregates of specific interest are particles, such as amicroscopic particle. This includes an aggregate that is capable ofbeing more readily taken up by the cell and expressed on the cellsurface compared to the corresponding non-aggregated derivative. By“corresponding non-aggregated derivative” is intended the samederivative found in the aggregate in reference. Aggregates are describedin more detail below.

In a related embodiment, the polysialic acid derivative employed in themethod is, or is capable of being expressed as a substantially intactantigen on the surface of the cancer cell. This includes, for example, apoly alpha (2→8) or poly alpha (2→9) N-acetyl neuraminic acid thatcontains a mixture of N-acetyl and de-N-acetyl residues, and thus anantigen that comprises a de-N-acetylated sialic acid epitope. Cancercells of interest include neuroblastoma, leukemia, and melanoma cells.In one embodiment, the cell is in a subject, such as a human, and iscontacted with antigen by administering to the subject an effectiveamount of a composition that comprises a polysialic acid derivative ofthe present disclosure. Various formulations, routes of administrationand dosing are described in more detail below. In a specific embodiment,the polysialic acid derivative is an aggregate, as described above andin more detail below.

Another method of the present disclosure is facilitating binding of anantibody to a mammalian cell. This method involves increasing the amountof the antigen on a cell as noted above, and then contacting the cellwith an antibody that is specific for the antigen so as to facilitatebinding of the antibody to the cell. This aspect includes variousembodiments such as where binding of the antibody to the cell isincreased, where antibody binding to the cell facilitates uptake of theantibody by the cell, and where uptake of the antibody by the cell isincreased. An additional embodiment is one in which binding of theantibody to the cell is cytotoxic, i.e., toxic to cells, includingarresting growth, inducing apoptosis, and/or inducing cell death. In aspecific embodiment, the antibody is specific for a de-N-acetylatedsialic acid epitope. An example of an antibody suitable for this purposeis SEAM 3.

Antibody employed in the methods of the present disclosure can be aconjugate of a first molecule to one or more second molecules, such as adetectable label, a cytotoxic drug, a toxin, such as an immunogenictoxin, and the like, such as described in more detail below. Here again,cells of interest include cancer cells such as neuroblastoma, leukemia,and melanoma cells, and where the cell can be in vitro or in vivo.

For instance, when in vitro, the cell can be in a format isolated orseparated from its normal environment, such as a cultured cell line andthe like. When the cell is in vitro, an effective amount of the antigencan be exogenously applied to the cell so as to facilitate expression ofthe antigen on the cell surface, and then the antibody can be broughtinto contact with the cell using an effective amount so as to facilitatebinding of the antibody to the cell. It will also be appreciated thatthe conditions under which in vitro binding is facilitated can beadjusted and are routine, for example, in various cell culture assaysand diagnostic procedures (e.g., such as the flow cytometry, ELISA andWestern Blot assays described herein), affinity purification schemes andthe like.

When in vivo, the cell is in a subject, such as a human, and iscontacted with antigen by administering to the subject an effectiveamount of a composition that comprises a polysialic acid derivative ofthe present disclosure. In some embodiments, contacting with theantibody may also be in vitro or in vivo. For instance, when theantibody is exogenously applied to a cell in a subject, the method mayinvolve administering to the subject an effective amount of the antibodyso as to affect binding of the antibody to the cell. Alternatively, theantibody may be one that is elicited by the subject, such as describedbelow, or a combination of exogenously applied and internally elicitedand thus brought into contact with antigen on the surface of a cell invivo in this manner. Various formulations, routes of administration anddosing for in vivo applications are described in more detail below.

The present disclosure also includes methods of eliciting antibody to acell in a subject. This method involves administering to the subject aneffective amount of an immunogenic composition that includes an antigenso as to increase expression of the antigen by the cell in the subject.This embodiment employs an antigen that comprises a polysialic acidderivative having a mixture of N-acetyl and de-N-acetyl residues andthat is resistant to degradation by exoneuraminidase. A specific featureof this method is where the antigen is an aggregate of the polysialicacid derivative, as described above and in more detail below. Theadministering is effective to elicit production of an antibody in thesubject that specifically binds to the cell. In one embodiment, bindingof the elicited antibodies to the cell can be cytotoxic, and thus arrestcell growth, induce apoptosis, and/or induce cell death. Typically, theantibody is specific for a de-N-acetylated sialic acid epitope, and thusthe antigen comprises de-N-acetylated sialic acid epitope. In a specificembodiment, the antigen is expressed on the surface of a cancer cellsuch as neuroblastoma, leukemia, or melanoma cell.

An additional method is for reducing the viability of a cancer cell.This method involves contacting a cancer cell with an effective amountof a composition comprising a polysialic acid derivative of the presentdisclosure so as to reduce the viability of the cell. In this embedment,the polysialic acid derivative has a reducing end and a non-reducingend, and is a substantially unoxidized and purified oligosaccharide. Thesubstantially unoxidized and purified oligosaccharide comprises (i) amixture of N-acetyl sialic acid and de-N-acetyl sialic acid residues,and (ii) a de-N-acetyl sialic acid residue at the non-reducing end thatis resistant to degradation by exoneuraminidase. In a particularembodiment, intracellular uptake by the cancer cell of the polysialicacid derivative is cytotoxic to the cancer cell. The effective amount ofthe polysialic acid derivate as applied to be cytotoxic to the cell isgenerally a concentration higher than is required to elicit antibodyagainst the antigen generated by application of the polysialic acidderivative, and is usually at a concentration that forms an aggregate,such as a cooperatively formed high molecular weight complex. Cells ofparticular interest include cancer cells, such as neuroblastoma,leukemia, and melanoma cells, and the cell can be in vitro or in vivo.

Methods of Production and Compositions

As summarized above, the disclosure provides methods of producingisolated poly alpha (2→8) N-acetyl neuraminic acid compositions thatcontain a mixture of N-acetyl and de-N-acetyl residues (that is,neuraminic acid-containing polysialic acid) suitable for use in themethods. This includes polysialic acid derivatives having a mixture ofN-acetyl and de-N-acetyl residues and that are resistant to degradationby exoneuraminidase, as well as those that additionally bear anon-reducing end enriched for de-N-acetyl residues, as well ascompositions enriched with such polysialic acid derivatives. As usedherein and unless specified otherwise, the term “polysialic acid” refersto alpha (2→8) and alpha (2→9) polysialic acid. Thus, for example, apolysialic acid derivative of the invention includes those that comprisea polymer of sialic and neuraminic acid monomers joined essentiallythrough alpha (2→8) or alpha (2→9) glycosidic linkages. One or more ofthe sialic and neuraminic acid monomers of a polysialic acid may bemodified or conjugated to a second molecule, such as a partially orfully O-acetylated monomer of sialic and/or neuraminic acid. Thecompositions also include aggregates of the polysialic acid derivatives,as well methods of their production.

One feature of the methods of production is that, unlike approacheswhich typically focus on incorporation non-native moieties such asN-propionyl groups, the present methods are exploited to generatederivatives with mixtures of natural N-acetyl (e.g., as found in sialicacid) and de-N-acetyl (e.g., as found in neuraminic acid) moieties toresemble antigens that are uniquely expressed on the surface of variousbacterial and cancer cells. Another feature of the methods is that theyyield polysialic acid derivatives resistant to degradation byexoneuraminidase, and can be exploited in particular embodiments toimpart non-reducing ends enriched with de-N-acetyl groups. Anotheraspect of the methods is that aggregates of the polysialic acidderivatives are more readily taken up by cells and expressed on the cellsurface compared to the corresponding non-aggregated derivative. It isbelieved that these various structural properties of the compositionsdescribed herein can uniquely translate into the functional propertiesobserved upon their exogenous application to cells, including theirability to be readily taken up by a cell and presented on the cellsurface as a substantially intact antigen. For instance, the appearanceof substantially intact antigen on the cell surface following exogenousexposure of the cells to a polysialic acid derivative of the presentdisclosure was observed relative to controls by various techniques asillustrated in the Examples.

In particular, a specific method contemplated herein for the productionof an isolated polysialic acid derivative involves: (i) providing afirst composition comprising de-N-acetylated polysialic acid; (ii)re-N-acetylating said de-N-acetylated polysialic acid to generate asecond composition comprising partially re-acetylated polysialic acidhaving a mixture of N-acetyl and de-N-acetyl residues; and then (iii)isolating from the second composition polysialic acid derivativeresistant to degradation by exoneuraminidase.

Polysialic acid precursors of particular interest are homopolymers, suchas a homopolymer of sialic acid, for example, colominic acid, and can bederived from natural sources or synthetic. In another embodiment, thepolysialic acid precursors can be obtained from polysialic acid of N.meningitidis or E. coli K1, or other suitable source of bacterialpolysialic acid. Thus, depending on the precursor material selected, theN-acetyl and de-N-acetyl residues can be advantageously selected. Forexample, in one embodiment, the de-N-acetyl residue is neuraminic acid.In another embodiment the N-acetyl residue is sialic acid. In anotherembodiment, the polysialic acid derivative is a homopolymer ofneuraminic acid and sialic acid. In other embodiments, the N-acetyland/or de-N-acetyl neuraminic acid is O-acetylated at one or morepositions, such as for a polysialic acid precursor obtained frompolysialic acid of N. meningitidis Serogroup C in which C7 and C8 areO-acetylated in the naturally occurring material. In this regard, thepresent disclosure provides for control of the level of acylation of thefinal product, and in particular, the ability to generate polysialicacid derivative that contains the desired mixture of de-N-acetyl andN-acetyl residues.

This includes a related embodiment in which the polysialic acidprecursor is selected so as to generate polysialic acid derivative thatcontains about 10% to 30% de-N-acetyl residues, about 70% to 90%N-acetyl residues, and in some instance, such as noted above,non-natural N-acyl derivatives in a proportion of about 10% to 20%. Insome embodiments, the polysialic acid precursor is selected so as togenerate a polysialic acid derivative containing about 10% to 80%de-N-acetyl residues, usually about 10% to about 60%, and in certainembodiments, about 1, 2, 3, 4 or 5 de-N-acetyl residues per polysialicacid chain, and in specific embodiments, about 1 de-N-acetyl residuesper polysialic acid chain. The present disclosure also includes apolysialic acid precursor selected so as to generate a polysialic acidderivative that contains a non-reducing end de-N-acetyl residue linkedthrough a glycosidic bond to a residue selected from an N-acetyl residueand an N-acylated residue other than an N-acetyl group, and where thepolysialic acid derivative is substantially unoxidized and purifiedoligosaccharide having a degree of polymerization of about 2-10.

In a related embodiment, the polysialic acid precursor of the presentdisclosure can also be modified with various non-natural N-acyl groups.For instance, the polysialic acid precursor may be the product ofbiosynthesis of a polysialic acid in cell culture where the growth mediais supplemented with a mixture of mannosamine derivatives (e.g.,N-trihaloacyl mannosamine) and acyl mannosamine (e.g., N-trihaloacetyland N-acetyl mannosame) in a desired ratio such that the precursormaterial expressed by the cells contains the desired mixture ofde-N-acetyl and N-acetyl residues, as well as the desired amount ofnon-natural N-acyl groups. For example, the precursor material in aspecific embodiment is selected so as to yield polysialic acidderivative to comprise about 10% to 30% de-N-acetyl residues. Anotherexample is where the precursor material is selected to generate apolysialic acid derivative containing about 10% to 80% de-N-acetylresidues, usually about 10% to about 60% de-N-acetyl residues, and insome instances about 1, 2, 3, 4 or 5 de-N-acetyl residue per polysialicacid chain, and in specific embodiments, about 1 de-N-acetyl residuesper polysialic acid chain. An additional example is where the polysialicacid precursor selected so as to generate a polysialic acid derivativecontaining a non-reducing end de-N-acetyl residue linked through aglycosidic bond to a residue selected from an N-acetyl residue and anN-acylated residue other than an N-acetyl group, and where thepolysialic acid derivative is substantially unoxidized and purifiedmannosamine containing oligosialic acid having a degree ofpolymerization of about 2-10.

In the re-N-acylation step of the method, partial re-N-acylationprovides for production of a polysialic acid derivative having fewerthan 90%, fewer than 85%, fewer than 84%, fewer than 80%, fewer than75%, fewer than 70%, fewer than 60%, or fewer than 55%, usually about10%, about 15%, about 16%, about 20%, about 25%, about 30%, about 40%,or about 45% N-acylated residues relative to the total residues of thecompound. In this regard, the methods can provide for control of thelevel of acylation of the final product, so as to provide polysialicacid derivative having a desired level of acylation. In general,reacylation is controlled or prevented by limiting the amount ofacylating reagent. As noted above, a particular embodiment of interestis polysialic acid derivative having about 10% to 30% de-N-acetylresidues.

Other approaches are possible as well, including re-N-acylation with amixture of amine protected group and acyl groups (e.g., trihaloacetyland acetyl groups) in a desired ratio such that the polysialic acidderivative contains fewer than 90%, fewer than 85%, fewer than 84%,fewer than 80%, fewer than 75%, fewer than 70%, fewer than 60%, fewerthan 55% amine protected residues, usually about 10%, about 15%, about16%, about 20%, about 25%, about 30%, about 40%, or about 45% amineprotected residues (e.g., N-trihaloacylated residues) relative to thetotal residues of the compound (where the compound generally contains atleast 10 or at least 20 residues). In this regard, the presentdisclosure provides for control of the level of acylation of the finalproduct after removal of the amine protecting group and avoidingundesirable side reactions with free amino groups, so as to provide apolysialic acid derivative having a desired level of acylation. Removalof the amine protecting groups for a free amine at the deprotectedresidue. In general, the proportion of de-N-acetyl residues iscontrolled by limiting the amount of amine protecting reagent (e.g, theamount of a trihaloacylting reagent). Here again, one embodiment ofspecific interest is the generation of polysialic acid derivativecontaining the desired mixture of de-N-acetyl and N-acetyl residues, aswell as the desired amount of non-natural N-acyl group as noted above.CMP-N-acylated sialic acid analogs and sialyltransferases may also beused in a semi-synthetic approach (e.g., Wakarchuk et al. (2008)Glycobiology 18:177).

In a specific embodiment, the first composition of the method ofproduction is provided by treating a polysialic acid precursor with astrong reducing agent (e.g., sodium borohydride) followed by a strongbase (e.g., sodium hydroxide) under conditions suitable forde-N-acetylating the precursor. The strong reducing agent converts thereducing end to the un-reactive alcohol form, which is followed bytreatment with strong base to de-N-acetylate the polymer.

The reaction mixture can then be purified by standard methods (e.g.,dialysis in water and lyophilized followed by ion exchange) so as toisolate the desired material from byproduct, side reactions and thelike. For example, the quality of the material and amount of sialic acidand de-N-acetyl sialic acid in the polysialic acid product may bedetermined at this point (e.g., by resorcinol assay, such as describedin the Examples), and/or tested for its ability to be taken up andexpressed as antigen on the surface of a cell, such as described below,for characterization, and release purposes and the like.

When coupled to the isolation of polysialic acid derivatives resistantto degradation by exoneuraminidase, the products are enriched with thedesired material and particularly well suited for increasing the antigencontent on the surface of a cell. A composition of particular interestgenerated by this method includes an isolated polysialic acid derivativehaving a non-reducing end that is enriched for de-N-acetyl residues andresistant to degradation by exoneuraminidase, as well as compositionsthat are enriched with mixtures of polysialic acid derivatives having anon-reducing end that is enriched for de-N-acetyl residues.

For instance, the method of production step of isolating polysialic acidderivative resistant to degradation by exoneuraminidase from the secondcomposition typically involves exposing the partially re-acetylatedpolysialic acid to exoneuraminidase, and then purifying the desiredpolysialic acid derivative. Exoneuraminidase of particular interest isan exosialidase from Arthrobacter ureafaciens (SIALIDASE A™, Prozyme,Hayward, Calif.). In this aspect, exoneuraminidase (exosialidase) cannotdegrade polysialic acid that terminates on the non-reducing end with ade-N-acetyl sialic acid residue (i.e., neuraminic acid) or one that isotherwise chemically blocked. Therefore, digestion of a preparation of apolysialic acid derivative that contains de-N-acetyl residues locatedthroughout the polymer with an exoneuraminidase will result indegradation of the polysialic acid except when the exoneuraminidaseencounters a de-N-acetyl residue. At that point, no further degradationof the polymer will occur. Also, the polysialic acid molecules that arenot degraded are likely to have a de-N-acetyl sialic acid residue at thenon-reducing end. Alternatively, the desired material can be isolated bystandard purification of derivative under conditions that select for aterminal non-reducing end that is blocked from degradation byexoneuraminidase, such as a terminal neuraminic acid residue and thelike.

Thus, in certain embodiments, the method of production can be used todirectly produce a desired polysialic acid derivative resistant todegradation by exoneuraminidase from precursor material appropriate forthis purpose. This method involves: (i) treating a first compositioncomprising polysialic acid derivative having a mixture of N-acetyl andde-N-acetyl residues with exoneuraminidase; and (ii) isolating from thefirst composition polysialic acid derivative resistant to degradation bysaid exoneuraminidase. This method is particularly suited when theprecursor material is appropriately selected and/or prepared to containa mixture of N-acetyl and de-N-acetyl residues, and then the desiredproduct purified and isolated away from the degradation products so asto avoid unwanted side reactions such as re-acetylation, aldehyde andketone side reactions, unwanted cross linking, as well as a wide rangeof other unwanted contaminants such as monomer and intermediatessusceptible to exoneuraminidase degradation, or that otherwise alter thedesired properties of the material. In this way the specific activity ofthe isolated polysialic acid derivative can be increased relative tounpurified material, and the benefits of higher specific activityexploited, including increased expression of the antigen of the surfaceof a cell when exogenously applied to the cell. By “specific activity”is intended the amount of antigen formed on the surface of a cell in agiven amount of time under given conditions per unit (e.g., microgram)of exogenously applied polysialic acid derivative, or calculated as theconcentration of polysialic acid derivative disappearing (or productproduced) per unit time following exogenous administration of thepolysialic acid derivative.

In a specific embodiment, the specific activity of a polysialic acidderivative having a mixture of de-N-acetyl and N-acetyl residues andthat is resistant to degradation to exoneuraminidase is greater than apolysialic acid that is susceptible to exoneuraminidase degradation. Inanother embodiment, the specific activity of a polysialic acidderivative having a mixture of de-N-acetyl and N-acetyl residues andthat is resistant to degradation to exoneuraminidase is greater than apolysialic acid that is not enriched for non-reducing end re-N-acetylresidues. In yet another embodiment, the specific activity of apolysialic acid derivative having a mixture of de-N-acetyl and N-acetylresidues and that is resistant to degradation to exoneuraminidase isgreater than a polysialic acid that is susceptible to exoneuraminidasedegradation and that is not enriched for non-reducing end re-N-acetylresidues. As can be appreciated, compositions produced by the presentmethod generate polysialic acid derivatives with greater specificactivity than previously observed for other derivatives, particularlywith respect to the relative uptake and presentation of polysialic acidantigen on the cell surface as a substantially intact antigen.

In another specific embodiment, compositions of the present disclosurecan be produced by (i) providing a solution comprising a mixture ofpolysialic acid derivatives each having: a different degree ofpolymerization, a different mixture of N-acetyl residues and de-N-acetylresidues, and a non-reducing end N-acetyl sialic acid residue; (ii)subjecting the solution to ion exchange chromatography to generatefractions; and (iii) isolating from one or more of the fractions apolysialic acid derivative having a defined degree of polymerization anda non-reducing end de-N-acetyl residue resistant to degradation byexoneuraminidase. In certain aspects, the mixture of polysialic acidderivatives further includes polysialic acid molecules having anon-reducing end N-acetyl group. In some embodiments, the polysialicacid derivative having a defined degree of polymerization is isolated inan individual fraction, or a pool of fractions formed by poolingselected fractions containing a polysialic acid derivative having adesired activity of interest. Of particular interest is an isolatedpolysialic acid derivative produced by the ion exchange method disclosedherein in which the isolated polysialic acid derivative (i) has a degreeof polymerization in a range selected from about 2 to about 10, and (ii)decreases the viability of Jurkat T-cell leukemia cells by at leastabout 20% when the isolated polysialic acid derivative is exogenouslyapplied to the cells in an aqueous solution at a concentration of about0.01 mM to about 15 mM, usually about 0.5 mM to about 10 mM, and wherethe decrease in viability is relative to control Jurkat T-cell leukemiacells that are not exogenously exposed to the derivative.

In particular embodiments, ion exchange chromatography is carried out ata pH range of between about 6.5 and about 10.0. In a specificembodiment, the ion exchange chromatography is anion exchangechromatography. In some embodiments, the anion exchange chromatographyis high pH anion-exchange chromatography (HPAC). In certain embodiments,the anion exchange chromatography utilizes DEAE, TMAE, QAE, or PEI. Inother embodiments, the anion exchange chromatography utilizes ToyopearlSuper Q 650M, MonoQ, Source Q or Fractogel TMAE. A particular ionexchange chromatography procedure of interest employs a resin such as QSepharose™ Fast Flow (strong anion), SP Sepharose™ Fast Flow (strongcation), CM Sepharose™ Fast Flow (weak cation), DEAE Sepharose™ FastFlow (weak anion), and ANX Sepharose™ 4 Fast Flow (high sub) (weakanion) (e.g., available from GE Healthcare Bio-Sciences Corp.,Piscataway, N.J.). Of specific interest are strong anion exchangers,such as Q Sepharose™ Fast Flow. Sample/loading buffer and elution systemfor such ion exchange columns and systems are generally selected forresolving the isolation of a particular compound of interest.

An example of a general buffer system for a Q Sepharose™ Fast Flow anionexchange resin is a sample/loading buffer system of 20 mM Bis-Trisbuffer, pH 8, and an elution buffer system composed of a 0M to 0.2Mgradient of sodium chloride in 20 mM Bis-Tris buffer, which can beeluted at different flow rates depending on column dimensions and thelike. The ion exchange fractions containing a de-N-acetyl and N-acetylsialic acid material of interest can be analyzed with great sensitivityby high pH anion-exchange chromatography with pulsed amperometricdetection (HPAC-PAD) (e.g., Townsend, R. R. (1995) Analysis ofglycoconjugates using high-pH anion-exchange chromatography. J.Chromatog. Library 58, 181-209; and Manzi et al., (1990) HPLC of sialicacids on a pellicular resin anion exchange column with pulsedamperometry. Anal. Biochem. 188, 20-32). The isolated material may bepurified further by one or more orthogonal chromatography techniquessuch as gel permeation, size exclusion, RP-HPLC and the like. Ifdesired, the isolated polysialic acid material can be subjected to oneor more of further preparatory steps, such dialysis, lyophilization,crystallization, formulation and the like.

The ion exchange and purification method described above can be carriedout on a mixture of polysialic acid derivative that is produced bytreating a first composition comprising a polysialic acid derivativehaving a mixture of N-acetyl and de-N-acetyl residues withexoneuraminidase. The method may also be carried out on a mixture ofre-acetylated polysialic acid derivatives, such as produced byre-acetylating a first composition comprising de-N-acetylated polysialicacid to generate a second composition, the second composition comprisingpartially re-acetylated polysialic acid having: a mixture of N-acetyland de-N-acetyl residues, and which is resistant to degradation byexoneuraminidase.

In a particular embodiment of interest, the ion exchange andpurification method described above is applied in the production andpurification of isolated polysialic acid derivative that issubstantially unoxidized and defined so as to have few side products inthe initial material subjected to ion exchange purification. Forinstance, unwanted oxidation of polysialic acid generates multipleoverlapping degradation and side reaction products that can be difficultto resolve and separate from the desired material by ion exchangechromatography. As such, “substantially unoxidized” is intended meanthat the polysialic acid derivative, excepting normal isomer or tautomerequilibriums, contains less than about 20%, less than about 15%, lessthan about 10%, less than about 5% oxidized sacchardide residues, andusually about 80%, about 85%, about 90%, about 95% or greater unoxidizedsacchardide residues. Of specific interest is a total chemical synthesismethod that generates an initial product containing few side reactionproducts, and facilitates the purification of smaller polysialic acidderivatives of defined length and composition.

In certain embodiments, the substantially unoxidized and definedpolysialic acid derivative is produced by time-controlledde-N-acetylation and/or non-oxidizing acid hydrolysis of a polysialicacid precursor material of interest. A featured aspect is a chemicalsynthesis method for the production of a substantially unoxidized anddefined polysialic acid derivative, where the method involves either (i)non-oxidizing acid hydrolysis of partially de-N-acetylated polysialicacid prepared by reduced time-controlled alkaline hydrolysis, or (ii)partial de-N-acetylation of polysialic acid by reduced time-controlledalkaline hydrolysis followed by non-oxidizing acid hydrolysis.

Partial de-N-acetylation of polysialic acid by time-controlled alkalinehydrolysis involves (i) treating a polysialic acid precursor with astrong reducing agent in a strong base under conditions suitable forpartially de-N-acetylating the precursor, where the treating is for aperiod of time effective to generate a minimally degraded product ofpartially de-N-acetylated polysialic acid. In certain embodiments, theperiod of time for treatment is about 1 hour or less, generally rangingfrom about 5-55 minutes in one minute increments, such as ranging fromabout 10-50 minutes, 15-45 minutes, 20-40 minutes, and usually about 40minutes. Thus, the reaction time can be selected to provide forminimally degraded product, generating desired fractions of partiallyde-N-acetylated polysialic acid separatable by ion exchangechromatography. An example of a suitable strong reducing agent for thisprocedure is sodium borohydride, sodium cyanogen borohydride and thelike (i.e., reagents that easily lose (or donate) electrons, such as inapproximate increasing order of strength: sodium cyanogenborohydride˜sodium triacetoxyborohydride, sodium borohydride, lithiumtri-sec-butylborohydride, and lithium aluminum hydride). An example of asuitable strong base is sodium hydroxide (i.e., a base which hydrolyzescompletely, raising the pH of the solution towards 14, and thus a basehaving a pKa of more than about 13, such as in approximate increasingorder of strength: potassium hydroxide, barium hydroxide, cesiumhydroxide, sodium hydroxide, strontium hydroxide, calcium hydroxide,lithium hydroxide, and rubidium hydroxide). The reaction may also beaided by selecting an appropriate temperature, usually ranging fromabout 70° C.-120° C., about 80° C.-110° C., and more typically about 90°C.-100° C. As such, alkaline de-N-acetylation can be carried out fordifferent reaction times to generate de-N-acetyl polysialic acidcontaining defined amounts of de-N-acetyl sialic acid residuesthroughout the polymer precursor, and to generate discrete fractionswith minimal overlapping degradation products. In addition, thetime-controlled partial alkaline de-N-acetylation procedure can generatepolysialic acid derivative containing desired amounts of de-N-acetylresidues, for example, about 25%-60% de-N-acetyl residues.

Non-oxidizing acid hydrolysis can be carried out to increase thefraction of chains containing de-N-acetyl sialic acid at thenon-reducing end, since the glycosidic bond at the reducing end of ade-N-acetyl sialic acid residue in polysialic acid is resistant tohydrolysis while the bond at the non-reducing end of the residue is not.In addition, performing the acid hydrolysis reaction under suchnon-oxidizing conditions minimizes oxidative damage to thepolysaccharide that can occur in the presence of strong acid or highconcentrations (10%) of acetic acid. Furthermore, non-oxidizing acidhydrolysis facilitates the production of smaller oligosialic acid (oroligosaccharide) derivatives enriched for de-N-acetyl sialic acidresidues at the non-reducing end. This aspect involves (i) exposing apolysialic acid precursor or a partially de-N-acetylated polysialic acidunder acidic conditions capable of selectively hydrolyzing a glycosidicbond of the polysialic acid, where the acidic conditions include abuffer solution in which dissolved gasses have been evacuated (e.g., byalternately freezing and thawing the solution under vacuum).Anti-oxidants and free radical scavengers may also be added to thereaction mixture to further reduce the oxidizing environment of thereaction solution. In addition to the non-oxidizing conditions, theacidic buffer system generally includes those suitable for acid-basedpolysialic acid hydrolysis reactions, for example, 0.1 M sodium acetatebuffer, pH 5.5. Additional examples of acidic conditions includehydrochloric acid (e.g., 20 mM HCl) and trifluroacetic acid (e.g., 0.1 MTFA). The non-oxidizing acid hydrolysis reaction can be carried out fordifferent periods of time, for a given end use, which is usually about1-30 hours, 5-25 hours, 10-20 hours, and generally about 15-18 hrs. Thetemperature of the reaction may also be adjusted to aid control of thereaction. Examples of suitable a temperature range is about 25° C. orgreater, such as a temperature range of about 40° C. to 90° C., usuallyabout 50° C. to 70° C. As such, the non-oxidizing acid hydrolysis methodis well suited for generating shorter length polysialic acid derivativeshaving a non-reducing end de-N-acetyl residue and a desired degree ofpolymerization, including for example, products with a defined degree ofpolymerization of about 2-20, usually of about 2-10.

Hence the products produced by the methods include certain featuresuseful for imparting an ability to be processed and presented on thesurface of a cell as a substantially intact antigen. Among thesefeatures, as noted above, is an isolated polymer or composition enrichedwith isolated polymers having a mixture of de-N-acetyl and N-acetylresidues and that is resistant to degradation to exoneuraminidase. Thusone feature that can improve presentation of the antigen includes thepurity of the material itself. For example, in a specific embodiment,the isolating steps of the production methods of the present disclosurecan generate product that is substantially free of contaminants, andthus enriched for the desired derivative relative to non-enrichedcontrols. This includes polysialic acid derivatives that have anincrease in the proportion of a desirable property or element. Forexample, isolation of a desired polysialic acid derivative is where thepolysialic acid of interest represents the majority of the desiredmaterial (e.g., more than 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%,95% or more up to 100%). This of course includes mixtures of polysialicacid derivatives having variable chain lengths, provided that themajority of chains each individually contain a mixture of de-N-acetyland N-acetyl residues and that is resistant to degradation toexoneuraminidase, as well as mixtures with these features and theadditional feature of having a non-reducing end that is enriched forde-N-acetyl residues, including for instance a de-N-acetylated residueat the non-reducing terminal end (i.e., a non-reducing end de-N-acetylsialic acid residue).

Again, depending of the specific approach, polysialic acid derivativecan be produced to have various beneficial structural and relatedfunctional properties, such as a non-reducing end having one or morede-N-acetyl residues, a terminal de-N-acetyl residue and the like. Asnoted above, a de-N-acetyl residue of specific interest is neuraminicacid, and thus the terminus of the non-reducing end can be neuraminicacid. As also noted above, the methods can be exploited to producepolysialic acid derivative in which the non-reducing end is enrichedwith de-N-acetyl residues, as well as homopolymers of neuraminic andsialic acid and the like. Polysialic acid derivative may also beproduced so as to comprise about 10% to 30% de-N-acetyl residues, or incertain embodiments, about 10% to 80% de-N-acetyl residues, andtypically about 10% to 70%, about 25% to 65%, about 40% to 60% to aconvergence of about 50% de-N-acetyl residues, as well as polysialicacid derivative that comprise a mixture of polysialic acid derivativechains of variable length. In certain embodiments, the methods ofproduction are suitable to produce a polysialic acid having about 1, 2,3, 4 or 5 de-N-acetyl residue per polysialic acid derivative chain, andin specific embodiments, about 1 de-N-acetyl residue per polysialic acidderivative chain. In addition, the production methods of the presentdisclosure may be employed to generate polysialic derivatives having adefined degree of polymerization, particularly for shorter polysialicacid derivatives, such as oligosialic acid derivatives having a degreeof polymerization of about 2 to about 20, such as a degree ofpolymerization of about 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,16, 17, 18, 19, 20 or 21. The compositions of the present disclosureinclude polysialic acid derivatives with these features.

Compositions of particular interest include an isolated polysialic acidderivative that is substantially unoxidized and comprises (i) a mixtureof N-acetyl sialic acid and de-N-acetyl sialic residues, and (ii) anon-reducing end de-N-acetyl residue that is resistant to degradation byexoneuraminidase, where the composition is substantially free ofpolysialic acid having a non-reducing end N-acetyl sialic acid residue.By composition is “substantially free of polysialic acid having anon-reducing end N-acetyl sialic acid residue” is intended to mean thatthe composition contains less than about 20%, less than about 15%, lessthan about 10%, or less than about 5% non-reducing end N-acetylresidues, and usually about 80%, about 85%, about 90%, about 95% orgreater non-reducing end de-N-acetyl residues.

In some embodiments, the isolated polysialic derivative of thecomposition has a degree of polymerization of about 2-20, such as adegree of polymerization selected from 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,12, 13, 14, 15, 16, 17, 18, 19, 20 and 21. In specific embodiments, theisolated polysialic derivative of the composition has a degree ofpolymerization of about 2-10, about 2-9, about 2-8, about 2-7, about2-7, about 2-6, about 2-5, about 2-4, about 2-3, or about 2. Thisincludes particular embodiments where the degree of polymerization is ofa range of about 3-5, about 3-6, about 3-7, about 3-8, about 4-6, about4-8, or about 4-10.

The isolated polysialic acid derivative of the compositions disclosedherein generally contains about 10% to 80% de-N-acetyl residues, usuallyabout 10% to about 60% de-N-acetyl residues, and in some instances about1, 2, 3, 4 or 5 de-N-acetyl residue per polysialic acid chain, and inspecific embodiments, about 1 de-N-acetyl residues per polysialic acidchain. An additional example is an isolated polysialic acid derivativeof the composition can contain a non-reducing end de-N-acetyl residuelinked through a glycosidic bond to a residue selected from an N-acetylresidue and an N-acylated residue other than an N-acetyl group, andwhere the polysialic acid derivative is substantially unoxidized andpurified. Of particular interest is a composition having an isolatedpolysialic acid derivative that (i) has a degree of polymerization of arange selected from about 2 to about 10, and (ii) decreases theviability of Jurkat T-cell leukemia cells by at least about 20% when theisolated polysialic acid derivative is exogenously applied to the cellsin an aqueous solution at a concentration of about 0.01 mM to about 15mM, usually about 0.5 mM to about 10 mM, and where the decrease inviability is relative to control Jurkat T-cell leukemia cells that arenot exogenously exposed to the derivative.

In certain embodiments, the isolated polysialic derivative of thecomposition can comprise at least one dimer of de-N-acetyl sialic acidand N-acetyl sialic acid linked through a glycosidic bond selected fromα(2→8) and α(2→9). Aspects of the composition include a polysialic acidderivative in which the non-reducing end de-N-acetyl sialic acid residueis linked through a glycosidic bond to an N-acetyl sialic acid residue.A featured aspect is where the de-N-acetyl sialic acid is neuraminicacid, and the N-acetyl sialic acid is N-acetyl neuraminic acid. Arelated embodiment is where at least one of the neuraminic acid andN-acetyl neuraminic acid residues comprises at least one O-acetylatedgroup. In a particular embodiment of interest, the isolated polysialicacid derivative is derivable from a capsular polysaccharide homopolymerof a bacterium selected from Escherichia coli K1, Escherichia Coli K92,Neisseria meningitidis Serogroup B, Neisseria meningitidis Serogroup C,Haemophilus ducreyi, Campylobacter jejuni, Moraxella catarrhalis,Streptococcus algalactiae, and Paterurella multocidae. Additionalsuitable polysialic acid materials may be employed (Troy, F.,Sialobiology and the Polysialic Acid Glycotype: Occurrence, Structure,Function, Synthesis, and Glycopathology, Chpt. 4, pp. 95-133, In Biologyof Sialic Acids, Abrahman Rosenburg, Ed., Springer, 1995). Aggregatesthe compounds, and compositions containing same, are also of interest.

Another embodiment is a method of producing a composition comprising anaggregate of one or more polysialic acid derivatives, as well as thecompositions produced by the methods. This method involves exposing apolysialic acid derivative to an aggregating condition so as to form anaggregate. Thus the methods of production described above may furtherinclude the step of forming an aggregate of the isolated polysialic acidderivative. Examples of the aggregating conditions include heating,addition of an excipient that facilitates aggregation, and the like.

By “aggregate” is intended a particle comprising an aggregated complexof individual monomers of a molecule and having a combined molecularweight that is a multiple of the molecular weight of an individualmonomer of the complex. For example, an aggregate of one or moremonomers of a polysialic acid derivative include an aggregate complexhaving a particle molecular weight that is 10× or more of the molecularweight of an individual monomer in the aggregated monomer complex. Thisincludes an aggregate having a particle with a molecular weight ofgreater than about 50,000, to greater than about 250,000 Daltons, togreater than 500,000 Daltons, to greater than 750,000 Daltons, togreater than 1,000,000 Daltons up to a particle having a uniformparticle size that is readily visible by light microscopy, e.g., under astandard low magnification light microscope (e.g., 40× magnification).

Thus, the aggregate can be a molecular or microscopic particle. Formicroscopic particles, the optimal aggregate can be selected by varyingthe mean aggregate diameter, e.g., 1 um to 20 μm, and usually about orsmaller than the diameter of a cell targeted for exposure and uptake ofthe material of interest, e.g., cells are usually approximately 1-20 μmin diameter. For non-visible molecular particles, as well as themicroscopic particles, the desired aggregate can be selected bymeasuring uptake and internalized by cells. In each instance, theaggregate of the polysialic acid derivative is capable of being taken upand internalized by cells better than non-aggregated derivative relativeto each other, a control, and/or both.

As noted above, the aggregate can be formed by admixing a non-aggregatedforms of one or more polysialic acid derivatives under aggregatingconditions, by partial degradation or partial hydrolysis of a polysialicacid derivative under aggregating conditions, forming an aggregate ofthe polysialic acid derivative with an aggregating excipient, or acombination thereof. By “aggregating condition” is intendedchemical-physical conditions that cause an otherwise soluble material toform an aggregated substance in solution. For instance, a polysialicacid derivative can be heated (e.g., 30° C.-70° C.) for an appropriateperiod of time (e.g., 1 hr to overnight) so as to form an aggregate.Typically, the temperature and duration of exposure are selected toreduce or inhibit microbial growth (e.g., reduce the potential forcontamination) while not destroying the desired activity of theaggregate.

In another embodiment, the polysialic acid derivative comprises anon-reducing end that is a de-N-acetyl residue, such as neuraminic acid,and the aggregate is formed by exposing the derivative to aggregatingconditions. Treatment with exoneuraminidase enriches for non-reducingend de-N-acetyl residues which aggregate when heated forming particlesthat are readily taken up by cells. This also applies to other polymersof sialic acid, including non-derivatized polysialic acid as well asderivatized polysialic acid. Accordingly, the present disclosure alsoprovides a method of producing an aggregate of a polysialic acid orpolysialic acid derivative. This method involves treating a polysialicacid or polysialic acid derivative exoneuraminidase so as to generatepolysialic acid or polysialic acid derivative having a non-reducing endthat is resistant to degradation by exoneuraminidase, exposing theexoneuraminidase treated material to aggregating conditions, andisolating the aggregate.

As noted above, aggregates of the present disclosure also include anaggregate of a polysialic acid derivative formed by the addition of oneor more excipients that are capable of facilitating aggregation of thederivative. Of particular interest are substances capable offacilitating aggregation such as aluminum hydroxide.

Accordingly, compositions of particular interest are those enriched forpolysialic acid derivative that comprises polymer chains with one ormore, and in certain embodiments all, of the following characteristics:(i) a mixture of N-acetyl and de-N-acetyl residues; (ii) resistance todegradation by exoneuraminidase; (iii) non-reducing end with one or moreof the de-N-acetyl residues residing therein; (iv) non-reducing end thatis itself enriched with de-N-acetyl residues; and (v) terminalnon-reducing end that is a de-N-acetyl residue. Compositions of specificinterest are those comprising an aggregate of a polysialic acidderivative, including an aggregate of individual or a mixture ofdifferent polysialic acid derivatives, and capable of being taken up bycells and expressed on the cell surface better than the correspondingnon-aggregated derivative, for example, as gauged by the amount of thepolysialic acid derivative present on the cell surface relative to theappropriate control.

Thus compositions of the present disclosure can include isolatedpolysialic acid derivative produced according to any of the methodsdescribed herein. Of specific interest is a composition that includes anisolated polysialic acid derivative that comprises a mixture of N-acetyland de-N-acetyl residues and that is resistant to degradation byexoneuraminidase, as well as compositions that include a polysialic acidderivative having a non-reducing end with one or more of the de-N-acetylresidues residing therein. As also noted above, other compositions ofinterest are those in which the polysialic acid derivative has anon-reducing end that is enriched with de-N-acetyl residues.

Additional compositions of interest include the following. Oneembodiment is a composition in which the polysialic acid derivativecomprises a mixture of polysialic acid derivative chains of variablelength. In another embodiment, the composition includes polysialic acidderivative that comprises about 10% to 30% de-N-acetyl residues. Othercompositions of interest include polysialic acid derivative that is ahomopolymer of neuraminic acid and sialic acid. In a specificembodiment, the homopolymer of neuraminic acid and sialic acid isproduced by partial re-acetylation of a de-acetylated homopolymer ofsialic acid. In these examples, a specific homopolymer of sialic acid ofinterest is colominic acid (i.e., capsular polysaccharide of obtainablefrom N. meningitidis Serogroup B). In another embodiment, thehomopolymer of sialic acid is obtainable from capsular polysaccharide ofN. meningitidis Serogroup C.

As noted above, conjugates of the polysialic acid derivates are ofinterest, and thus the production methods disclosed herein may furtherinclude the step of conjugating a second molecule. In this aspect, theisolated polysialic acid derivative is conjugated to a second molecule,such as a protecting group, amino acid, peptide, polypeptide, lipid,carbohydrate, nucleic acid, detectable label and the like. An advantageof polysialic acid derivatives that are conjugated to another moleculeincludes the ability to retain the desired activity, while exploitingproperties of the second molecule of the conjugate to impart anadditional desired characteristic. For example, the polysialic acidderivatives can be conjugated to a second molecule such as a peptide,polypeptide, lipid, carbohydrate and the like that aids in solubility,storage or other handling properties, cell permeability, half-life,controls release and/or distribution such as by targeting a particularcell (e.g., neurons, leucocytes etc.) or cellular location (e.g.,lysosome, endosome, mitochondria etc.), tissue or other bodily location(e.g., blood, neural tissue, particular organs etc.). Other examplesinclude the conjugation of a dye, fluorophore or other detectable labelsor reporter molecules for assays, tracking and the like. Morespecifically, the polysialic acid derivatives described herein can beconjugated to a second molecule such as a peptide, polypeptide, dye,fluorophore, nucleic acid, carbohydrate, lipid and the like (e.g., ateither the reducing or non-reducing end), such as the attachment of alipid moiety, including N-fatty acyl groups such as N-lauroyl, N-oleoyl,fatty amines such as dodecyl amine, oleoyl amine, and the like (e.g.,see U.S. Pat. No. 6,638,513)).

Other features of the conjugates can include one where the conjugatereduces toxicity relative to unconjugated polysialic acid derivative. Infurther embodiments, the conjugate targets a cancer cell relative tounconjugated material. Additional examples include a conjugate thepolysialic acid derivative with one or more molecules that complement,potentiate, enhance or can otherwise operate synergistically inconnection with the polysialic acid derivative. For instance, thepolysialic acid derivative can optionally have attached an anti-cancerdrug for delivery to a site of a cancer cell to further facilitate tumorkilling or clearance, e.g., an anti-proliferation moiety (e.g., VEGFantagonist, e.g., an anti-VEGF antibody), a toxin (e.g., an anti-cancertoxin, e.g., ricin, Pseudomonas exotoxin A, and the like), radionuclide(e.g. 90Y, 131I, 177L, 10B for boron neutron capture, and the like),anti-cancer drugs (e.g. doxorubicin, calicheamicin, maytansinoid DM1,auristatin caupecitabine, 5-fluorouricil, leucovorin, irinotercan, andthe like), and/or can optionally be modified to provide for improvedpharmacokinetic profile (e.g., by PEGylation, hyperglycosylation, andthe like).

Conjugates also include polysialic acid derivatives having one or morere-N-acetylated residues as noted above. For example, a re-N-acetylatedresidue of specific interest comprises an amino protecting group.Exemplary amino protecting groups include, but are not necessarilylimited to, carbamates, amides, N-alkyl and N-aryl amines, iminederivatives, enamine derivatives, N-sulfonyls, and the like. Furtherexemplary amine protecting groups include, but are not necessarilylimited to: acyl types such as formyl, trifluoroacetyl, phthalyl, andp-toluenesulfonyl; aromatic carbamate types such as benzyloxycarbonyl(Cbz) and substituted benzyloxy-carbonyls,1-(p-biphenyl)-1-methylethoxy-carbonyl, and 9-fluorenylmethyloxycarbonyl(Fmoc); aliphatic carbamate types such as tert-butyloxycarbonyl (tBoc),ethoxycarbonyl, diisopropylmethoxycarbonyl, and allyloxycarbonyl; cyclicalkyl carbamate types such as cyclopentyloxycarbonyl andadamantyloxycarbonyl; alkyl types such as triphenylmethyl and benzyl;trialkylsilane such as trimethylsilane; and thiol containing types suchas phenylthiocarbonyl and dithiasuccinoyl. Amine protecting groups andprotected amine groups are described in, e.g., C. B. Reese and E.Haslam, “Protective Groups in Organic Chemistry,” J. G. W. McOmie, Ed.,Plenum Press, New York, N.Y., 1973, Chapters 3 and 4, respectively, andT. W. Greene and P. G. M. Wuts, “Protective Groups in OrganicSynthesis,” Second Edition, John Wiley and Sons, New York, N.Y., 1991,Chapters 2 and 3.

A particular embodiment of interest is where the second molecule is animmunomodulator. By “immunomodulator” is intended a molecule thatdirectly or indirectly modifies an immune response. A specific class ofimmunomodulators includes those that stimulate or aid in the stimulationof an immunological response. Examples include antigens and antigencarriers such as a toxin or derivative thereof, including tetanustoxoid. Another embodiment includes a polysialic acid derivativecomposition that contains one or more immunogenic excipients; in thisembodiment, the polysialic acid derivative can be conjugated or not.Other examples include pharmaceutical compositions for use as vaccines,anti-cancer therapeutics that contain a polysialic acid derivative ofthe present disclosure, as well as use of the derivatives for thegeneration of antibodies and the like.

Accordingly, the non-conjugated and conjugated polysialic acidderivatives disclosed herein have many uses. For example, the polysialicacid derivatives of the present disclosure find use in generatingantigen on the surface of a cell, which can be exploited in various waysfor treatment of a subject, including inhibiting the growth of cancerouscells in a subject that bears a de-N-acetylated sialic acid (deNAc SA)epitope. By a “deNAc SA epitope” is intended a molecule that has (i)maximal cross-reactivity with an antibody against polysialic acid inwhich one or more residues is a de-N-acetyl neuraminic acid residue, and(ii) has minimal to no cross-reactivity with an antibody against normalpolysialic acid, especially as presented on a non-cancerous mammalian,e.g., human, cell surface. Thus the minimal deNAc SA epitope is adisaccharide of sialic acid residues in which one or both residuescontain a free amine at the C5 amino position; when one of the tworesidues is de-N-acetylated, the second residue contains an N-acetylgroup (but, in some embodiments, not an N-propionyl group). Thedisaccharide unit defining this minimal epitope may be at the reducingend, the non-reducing end, or within a polymer of sialic acid residues(e.g., within a polysaccharide). A deNAc SA epitope of specific interestis a disaccharide of sialic acid residues in which one residue containsa free amine at the C5 amino position (i.e., a de-N-acetyl sialic acidresidue), the second residue contains an N-acetyl group (i.e., aN-acetyl sialic acid residue), and the de-N-acetyl sialic acid residueof the disaccharide is at the non-reducing end.

De-N-acetylated residues in the context of PSA containing N-acylatedresidues are immunogenic and elicit antibodies that are reactive withthe deNAc SA epitope, but are minimally reactive or not detectablyreactive with human PSA antigens. For example, the de-N-acetylated NmBpolysaccharide epitope was identified using a murine anti-N-propionylNeisseria meningitidis group B (N—Pr NmB) polysaccharide mAb (monoclonalantibodies), SEAM 3, described in Granoff et al., 1998, J Immunol160:5028 (anti-N—Pr NmB PS mAbs); U.S. Pat. No. 6,048,527 (anti-NmBantibodies); and U.S. Pat. No. 6,350,449 (anti-NmB antibodies).

As noted above, another embodiment is a composition comprising anaggregate of a polysialic acid derivative of the present disclosure.This includes compositions that include an aggregate complex of apolysialic acid derivative having a particle molecular weight that is10× or more of the molecular weight of an individual polysialic acidderivative in the aggregated monomer complex. This includes acomposition comprising an aggregate having a particle with a molecularweight of greater than about 50,000, to greater than about 250,000Daltons, to greater than 500,000 Daltons, to greater than 750,000Daltons, to greater than 1,000,000 Daltons up to a particle having auniform particle size that is readily visible under a standard lowmagnification light microscope (e.g., 40× magnification). Of specificinterest is a composition comprising an aggregate can be a molecular ormicroscopic particle. This includes a composition comprising amicroscopic particle having a particle diameter of about 1 um to 20 μm.This also includes a composition comprising a microscopic particlehaving a particle diameter that is about or smaller than the diameter ofa cancer cell. Thus, the aggregate compositions contain an aggregate ofpolysialic acid derivative capable of being taken up and internalized bycells better than non-aggregated derivative relative to each other, acontrol, and/or both, including as measured by inhibition of cell growthfollowing exposure to anti-de-N-acetyl sialic acid antigen antibody. Theaggregate compositions can be formulated as described in more detailbelow, including as liquids, powders and the like.

In the methods of treatment of cancer, administering of polysialic acidderivative or an immunogenic composition that includes such derivativefacilitates a reduction in viability of cancerous cells exposed to thepolysialic acid derivative. Advantages of these methods are that thepolysialic acid derivatives can directly or indirectly facilitatedelivery of antibodies that are cytotoxic to cancer cells containing adeNAc SA epitope, for example, by increasing the amount of the deNAc SAepitope on the cell surface. This in turn can be a target for thesubject's own immune system and/or an antibody-based therapy such asSEAM 3. Another advantage is that the cytotoxicity of the polysialicacid derivative of the present disclosure can be dose dependent, andthus adjustable. Specific examples of cancerous cells amenable totreatment include melanoma, leukemia, or neuroblastoma cells.

In a related embodiment, the subject being treated possesses a deNAc SAepitope. The epitope can be present inside a cell or expressed on thecell surface, such as a cancer cell. This aspect can be beneficial inthat cells expressing or presenting a deNAc SA epitope can be moreamenable to treatment with a polysialic acid derivative of the presentdisclosure. For example, the cells can be contacted with polysialic acidderivative to increase de-N-acetyl sialic acid antigen on their surface,making them “visible” to the host immune system or immunotherapy. Ofcourse the derivatives can be administered to a subject that is naïvewith respect to a de-N-acetyl sialic acid antigen, for example, wheretherapy is initiated at a point where presence of the epitope is notdetectable, and thus is not intended to be limiting. It is also possibleto initiate polysialic acid derivative therapy prior to the first signof disease symptoms, at the first sign of possible disease, or prior toor after diagnosis of a primary cancer and/or metastases of a cancerhaving a detectable deNAc SA epitope (e.g., a ganglioside or otherglycoconjugate that is at least partially de-N-acetylated).

Another embodiment involves screening for the deNAc SA epitope incombination with polysialic acid derivative therapy. In this method,cells from a subject undergoing treatment, or being tested forsusceptibility to treatment, with polysialic acid derivative arescreened for the presence of a deNAc SA epitope. This can beaccomplished using an antibody or antibody fragment that binds to theepitope (e.g., an antibody specific for an polysialic acid derivative ofthe present disclosure, or a SEAM 3 monoclonal antibody (ATCC DepositNo. HB-12170)). As with cancer therapies in general, an advantage ofthis approach is the ability to select individuals with a cellularproliferation disorder or stage of disorder likely to be more responsiveto polysialic acid derivative therapy compared to those that are not.Another advantage of targeting a subject with cells bearing a deNAc SAepitope is that progress over the treatment course can be monitored, andtherapy, including dosing regimens, amounts and the like can be adjustedaccordingly.

Routes of administration (path by which the polysialic acid derivativeis brought into contact with the body) may vary, where representativeroutes of administration for the polysialic acid derivative aredescribed in greater detail below. In certain embodiments, thepolysialic acid derivative is administered by infusion or by localinjection. For example, where the tumor is a solid tumor, the polysialicacid derivative can be administered to a site adjacent or in the tumorbed. The polysialic acid derivative also can be administered prior, atthe time of, or after other therapeutic interventions, such as surgicalintervention to remove cancerous cells. The polysialic acid derivativecan also be administered as part of a combination therapy, in which atleast one of an immunotherapy, a cancer chemotherapy or a radiationtherapy is administered to the subject (as described in greater detailbelow).

In general the methods disclosed herein can involve administration of aneffective amount of a polysialic acid derivative to a subject in needthereof. In particular, polysialic acid derivatives of specific interestare those that increase the amount of intact antigen on the surface of acancer cell in a host when the compounds are administered in aneffective amount according to the present disclosure. The amountadministered varies depending upon the goal of the administration, thehealth and physical condition of the individual to be treated, age, thetaxonomic group of individual to be treated (e.g., human, non-humanprimate, primate, etc.), the degree of resolution desired, theformulation of the polysialic acid derivative composition, the treatingclinician's assessment of the medical situation, and other relevantfactors. It is expected that the amount will fall in a relatively broadrange that can be determined through routine trials.

For example, the amount of polysialic acid derivative employed toincrease the amount of intact antigen on the surface of a cancer cell ina host is not more than about the amount that could otherwise beirreversibly toxic to the subject (i.e., maximum tolerated dose). Inother cases the amount is around or even well below the toxic threshold,but still in a desired concentration range, or even as low as thresholddose. Thus in embodiments involving use of the polysialic acidderivatives to elicit an immunoprotective and/or immunotherapeuticimmune response against a cancer cell and/or a bacterial infection(e.g., Neisseria and/or E. coli K1), the amount of polysialic acidderivative administered is an amount effective to elicit animmunoprotective or immunotherapeutic immune response in the subjectagainst a cancer cell and/or bacterial infection, where the amount toeffect such immune response may vary according to a variety ofsubject-specific factors, such as those exemplified above. Where thepolysialic acid derivative is administered to effect an anti-deNAc SAantibody response, the antibodies elicited can provide for specificbinding of deNAc SA epitopes on a target antigen with little or nodetectable binding to host-derived polysialic acid.

Individual doses are typically not less than an amount required toproduce a measurable effect on the subject, and may be determined basedon the pharmacokinetics and pharmacology for absorption, distribution,metabolism, and excretion (“ADME”) of the polysialic acid derivative,and thus based on the disposition of the composition within the subject.This includes consideration of the route of administration as well asdosage amount, which can be adjusted for topical (applied directly whereaction is desired for mainly a local effect), enteral (applied viadigestive tract for systemic or local effects when retained in part ofthe digestive tract), or parenteral (applied by routes other than thedigestive tract for systemic or local effects) applications. Forinstance, administration of the polysialic acid derivative is typicallyvia injection and often intravenous, intramuscular, intratumoral, or acombination thereof, so as to avoid hydrolysis in the stomach.

Disposition of the polysialic acid derivative and its correspondingbiological activity within a subject can be gauged against the fractionof polysialic acid derivative present at a target of interest. Forexample, a polysialic acid derivative once administered can accumulateas a component of a glycoconjugate or other biological target thatconcentrates the material in a target cells and tissue, such as a cancercell and cancerous tissue. Thus dosing regimens in which the polysialicacid derivative is administered so as to accumulate in a target ofinterest over time can be part of a strategy to allow for lowerindividual doses. This can also mean that the dose of polysialic acidderivative that are cleared more slowly in vivo can be lowered relativeto the concentrations calculated from in vitro assays (e.g., effectiveamount in vitro approximates mM concentration, versus less than mMconcentrations in vivo).

As an example, the effective amount of a dose or dosing regimen can begauged from the IC50 of a given polysialic acid derivative for bindingof SEAM 3 to the cell surface antigen (i.e., SEAM 3 binding andinhibition of cell growth proportional to the polysialic acid antigenpresent on the cell surface). By “IC50” is intended the concentration ofa drug required for 50% inhibition in vitro. Alternatively, theeffective amount can be gauged from the EC50 of a given polysialic acidderivative. By “EC50” is intended the plasma concentration required forobtaining 50% of a maximum effect in vivo.

In general, with respect to the polysialic acid derivatives disclosedherein, an effective amount is usually not more than 200× the calculatedIC50. Typically, the amount of a polysialic acid derivative that isadministered is less than about 200×, less than about 150×, less thenabout 100× and many embodiments less than about 75×, less than about60×, 50×, 45×, 40×, 35×, 30×, 25×, 20×, 15×, 10× and even less thanabout 8× or 2× than the calculated IC50. In one embodiment, theeffective amount is about 1× to 50× of the calculated IC50, andsometimes about 2× to 40×, about 3× to 30× or about 4× to 20× of thecalculated IC50. In other embodiments, the effective amount is the sameas the calculated IC50, and in certain embodiments the effective amountis an amount that is more than the calculated IC50.

In other embodiments, an effect amount is not more than 100× thecalculated EC50. For instance, the amount of polysialic acid derivativethat is administered is less than about 100×, less than about 50×, lessthan about 40×, 35×, 30×, or 25× and many embodiments less than about20×, less than about 15× and even less than about 10×, 9×, 9×, 7×, 6×,5×, 4×, 3×, 2× or 1× than the calculated EC50. In one embodiment, theeffective amount is about 1× to 30× of the calculated EC50, andsometimes about 1× to 20×, or about 1× to 10× of the calculated EC50. Inother embodiments, the effective amount is the same as the calculatedEC50, and in certain embodiments the effective amount is an amount thatis more than the calculated EC50.

Effective amounts can readily be determined empirically from assays,from safety and escalation and dose range trials, individualclinician-patient relationships, as well as in vitro and in vivo assayssuch as those described herein and illustrated in the Experimentalsection, below.

The polysialic acid derivative can be administered to the subject incombination with one or more other therapies. For example, a therapy ortreatment other than administration of polysialic acid derivativecomposition can be administered anywhere from simultaneously to up to 5hours or more, e.g., 10 hours, 15 hours, 20 hours or more, prior to orafter the polysialic acid derivative. In certain embodiments, thepolysialic acid derivative and other therapeutic intervention areadministered or applied sequentially, e.g., where the polysialic acidderivative is administered before or after another therapeutictreatment. In yet other embodiments, the polysialic acid derivative andother therapy are administered simultaneously, e.g., where thepolysialic acid derivative and a second therapy are administered at thesame time, e.g., when the second therapy is a drug it can beadministered along with the polysialic acid derivative as two separateformulations or combined into a single composition that is administeredto the subject. Regardless of whether administered sequentially orsimultaneously, as illustrated above, the treatments are considered tobe administered together or in combination for purposes of the presentdisclosure.

Polysialic acid derivatives which find use in the present methods andmay be present in the compositions include, but are not limited to thosewith appropriate specificity and antigenicity so as to elicit anantibody that affects the growth of a cancer cell in a subject. As such,polysialic acid derivatives with such specificity aid in achieving theintended end result of modifying cellular proliferation of a cancer cellwhile minimizing unwanted side effects and toxicity. Put differently,the polysialic acid derivatives employed need not be identical to thosedisclosed in the Examples section below, so long as the polysialic acidderivatives are able to elicit an immune response against and/or inhibitgrowth of the target cell. Thus, one of skill will recognize that anumber of polysialic acid derivatives (described in more detail below),can be made without substantially affecting the activity of thepolysialic acid derivatives. This includes compositions ofpharmaceutically acceptable salts (e.g., hydrochloride, sulfate salts),solvates (e.g., mixed ionic salts, water, organics), hydrates (e.g.,water). For the polysialic acid compositions, they may be provided inprodrug forms thereof (e.g., esters, acetyl forms), anomers (e.g., α/βmutarotation), tautomers (e.g., keto-enol tautomerism) and stereoisomers(e.g., β-D-isomer). It also includes various polysialic acid derivativecompositions that contain one or more immunogenic excipients, such as anadjuvant, carrier and the like, as well as non-immunogenic polysialicacid derivative compositions that are essentially devoid of adjuvant orother immunogenic excipients.

The present disclosure includes prodrugs of the polysialic acidderivatives disclosed herein. Such prodrugs are in general functionalderivatives of the compounds that are readily convertible in vivo intothe required compounds. Thus, in the methods disclosed herein, the term“administering” encompasses administering the compound specificallydisclosed or with a compound which may not be specifically disclosed,but which converts to the specified compound in vivo afteradministration to the subject in need thereof. Conventional proceduresfor the selection and preparation of suitable prodrug derivatives aredescribed, e.g., in Wermuth, “Designing Prodrugs and Bioprecursors” inWermuth, ed. The Practice of Medicinal Chemistry, 2d Ed., pp. 561-586(Academic Press 2003). Prodrugs include esters that hydrolyze in vivo(e.g., in the human body) to produce a compound described hereinsuitable for the present disclosure. Suitable ester groups include,without limitation, those derived from pharmaceutically acceptable,aliphatic carboxylic acids, particularly alkanoic, alkenoic,cycloalkanoic and alkanedioic acids, in which each alkyl or alkenylmoiety has no more than 6 carbon atoms. Illustrative esters includeformates, acetates, propionates, butyrates, acrylates, citrates,succinates, and ethylsuccinates.

Whether or not a given polysialic acid derivative or conjugate thereofis suitable for use according to the present disclosure can be readilydetermined using various assays, such as those employed in theExperimental section, below. Generally, an polysialic acid derivative issuitable for use in the methods disclosed herein if it elicits an immuneresponse in a subject that facilitates inhibition of growth of a targetcell by at least about 2 to 10-fold, usually by at least about 50-foldand sometimes by at least about 100-fold to 200-fold relative to anormal control cell, as determined using the cell based assays, such asthose described in the Experimental section, below. In certainembodiments, an polysialic acid derivative is one that facilitates(e.g., through eliciting an anti-polysialic acid derivative antibodyand/or through increasing deNAc SA antigen on a cancer cell) reductionin viability of a target cell (such as a particular cancer cell or cellline), arrests growth and/or induces apoptosis of a target cell, and/orinduces cell death, as observed in the cell-based assays described inthe Experimental section below when generating an immune responseagainst the cell (e.g., cytotoxicity from enhancing deNAc SA epitope ofa cancer cell, and making it more susceptible to killing by a secondaryantibody such as described herein or SEAM 3, and/or one or more aspectsof the immune system).

It will also be appreciated that once isolated, some of the smallerpolysialic acid derivatives can be characterized and made by othertechniques, including standard chemical synthesis. For instance, suchpolysialic acid derivatives can be prepared conventionally by techniquesknown to one of skill in the art, including as described herein and inthe Examples. Representative references describing various synthesisapproaches, intermediates, precursors, analysis, as well as thesynthesis and preparation of conjugates, diagnostics and the like,include U.S. Pat. Nos. 4,315,074; 4,395,399; 4,719,289; 4,806,473;4,874,813; 4,925,796; 5,180,674; 5,246,840; 5,262,312; 5,278,299;5,288,637; 5,369,017; 5,677,285; 5,780,603; 5,876,715; 6,040,433;6,133,239; 6,242,583; 6,271,345; 6,323,339; 6,406,894; 6,476,191;6,538,117; 6,797,522; 6,927,042; 6,953,850; 7,067,623; and 7,129,333;the disclosures of which are herein incorporated by reference. See also,the following references: “Solid Support Oligosaccharide Synthesis andCombinatorial Carbohydrate Libraries,” Peter H. Seeberger Ed,Wiley-Interscience, John Wiley & Sons, Inc, NY, 2001; Plante et al.,Science (2001) 291(5508):1523; Marcaurelle et al., Glycobiology, 2002,12(6): 69R-77R; Sears et al., Science (2001) 291:2344-2350; Bertozzi etal., Chemical Glycobiology (2001) Science 291:2357-2364; MacCoss et al.,Org. Biomol. Chem., 2003, 1:2029; and Liang et al. Science (1996)274(5292):1520; Kayser et al J. Biol. Chem. 1992 267:16934, Keppler etal Glycobiology 2001, 11:11R; Luchansky et al Meth. Enzymol. 2003,362:249; Oetke et al Eur. J. Biochem. 2001, 268:4553; andWO/1997/045436; the disclosures of which are herein incorporated byreference.

Pharmaceutically acceptable salts of the polysialic acid derivatives canbe prepared by treating the free acid with an appropriate amount of apharmaceutically acceptable base. Representative pharmaceuticallyacceptable bases are ammonium hydroxide, sodium hydroxide, potassiumhydroxide, lithium hydroxide, calcium hydroxide, magnesium hydroxide,ferrous hydroxide, zinc hydroxide, copper hydroxide, aluminum hydroxide,ferric hydroxide, isopropylamine, trimethylamine, diethylamine,triethylamine, tripropylamine, ethanolamine, 2-dimethylaminoethanot,2-diethylaminoethanol, lysine, arginine, histidine, and the like. Thereaction is conducted in water, alone or in combination with an inert,water-miscible organic solvent, at a temperature of from about 0° C. toabout 100° C., and can be at room temperature. The molar ratio ofcompounds of general structure I to base used are chosen to provide theratio desired for any particular salts. For preparing, for example, theammonium salts of the free acid starting material, the starting materialcan be treated with approximately one equivalent of pharmaceuticallyacceptable base to yield a neutral salt. When calcium salts areprepared, approximately one-half a molar equivalent of base is used toyield a neutral salt, while for aluminum salts, approximately one-thirda molar equivalent of base will be used.

Pharmaceutical Formulations

Also provided are pharmaceutical compositions containing the polysialicacid derivatives employed in the methods of treatment disclosed herein.The term “polysialic acid derivative composition” is used herein as amatter of convenience to refer generically to compositions comprising apolysialic acid derivative of the present disclosure, includingconjugated polysialic acid derivatives, or both. Compositions useful forfacilitating modification of the growth of cancer cells are particularlycontemplated.

The polysialic acid derivative compositions, e.g., in the form of apharmaceutically acceptable salt, can be formulated for oral, topical orparenteral administration, as described above. In certain embodiments,e.g., where an polysialic acid derivative is administered as a liquidinjectable (such as in those embodiments where they are administeredintravenously or directly into a tissue), an polysialic acid derivativeformulation is provided as a ready-to-use dosage form, or as areconstitutable storage-stable powder or liquid composed ofpharmaceutically acceptable carriers and excipients.

Methods for producing and formulating polysialic acid derivativessuitable for administration to a subject (e.g., a human subject) arewell known in the art. For example, polysialic acid derivatives can beprovided in a pharmaceutical composition comprising an effective amountof a polysialic acid derivative and a pharmaceutical excipients (e.g.,saline). The pharmaceutical composition may optionally include otheradditives (e.g., buffers, stabilizers, preservatives, and the like). Aneffective amount of polysialic acid derivative can be an amounteffective to provide for enhancing a de-N-acetyl sialic acid antigen ona cancer cell and/or eliciting an immune response against suchde-N-acetyl sialic acid antigen-enhanced cancer cells. In otherembodiments, an effective amount of polysialic acid derivative is anamount that, particularly when administered with an adjuvant, providesfor an anti-polysialic acid derivative immune response so as to providefor an anti-bacterial or anti-cancer response in a subject for a desiredperiod. A therapeutic goal (e.g., reduction in bacterial or tumor load,or immunization) can be accomplished by single or multiple doses undervarying dosing regimen.

By way of illustration, the polysialic acid derivative compositions canbe admixed with conventional pharmaceutically acceptable carriers andexcipients (i.e., vehicles) and used in the form of aqueous solutions,tablets, capsules, elixirs, suspensions, syrups, wafers, patches and thelike, but usually the polysialic acid derivative will be provided as aninjectable. Such pharmaceutical compositions contain, in certainembodiments, from about 0.1 to about 90% by weight of the activecompound, and more generally from about 1 to about 30% by weight of theactive compound. The pharmaceutical compositions may contain commoncarriers and excipients, such as corn starch or gelatin, lactose,dextrose, sucrose, microcrystalline cellulose, kaolin, mannitol,dicalcium phosphate, sodium chloride, and alginic acid. Disintegratorscommonly used in formulations include croscarmellose, microcrystallinecellulose, corn starch, sodium starch glycolate and alginic acid.Preservatives and the like may also be included.

The polysialic acid derivative compositions can be provided in apharmaceutically acceptable excipient, which can be a solution such asan aqueous solution, often a saline solution, or they can be provided inpowder form. The polysialic acid derivative compositions may compriseother components, such as pharmaceutical grades of mannitol, lactose,starch, magnesium stearate, sodium saccharin, talcum, cellulose,glucose, sucrose, magnesium, carbonate, and the like. The compositionsmay contain pharmaceutically acceptable auxiliary substances as requiredto approximate physiological conditions such as pH adjusting andbuffering agents, toxicity adjusting agents and the like, for example,sodium acetate, sodium chloride, potassium chloride, calcium chloride,sodium lactate and the like.

The concentration of polysialic acid derivative in the pharmaceuticalformulations can vary from less than about 0.1%, usually at or at leastabout 2% to as much as 20% to 50% or more by weight, and will beselected primarily by fluid volumes, viscosities, etc., in accordancewith the particular mode of administration selected and the patient'sneeds. The resulting compositions may be in the form of a solution,suspension, tablet, pill, capsule, powder, gel, cream, lotion, ointment,aerosol or the like.

In general, administration of a polysialic acid derivative compositionis accomplished by any suitable route, including administration of thecomposition orally, bucally, nasally, nasopharyngeally, parenterally,enterically, gastrically, topically, transdermally, subcutaneously,intramuscularly, in tablet, solid, powdered, liquid, aerosol form,locally or systemically, with or without added excipients. Actualmethods for preparing parenterally administrable compositions will beknown or apparent to those skilled in the art and are described in moredetail in such publications as Remington's Pharmaceutical Science, 18thed., Mack Publishing Company, NY (1995).

It is recognized that when administered orally, polysialic acidderivatives should be protected from digestion. This is typicallyaccomplished either by complexing the polysialic acid derivative with acomposition to render it resistant to acidic and enzymatic hydrolysis orby packaging in an appropriately resistant carrier such as a liposome.Means of protecting a compound of interest from digestion are well knownin the art.

In order to enhance serum half-life, polysialic acid derivativepreparations that are injected may also be encapsulated, introduced intothe lumen of liposomes, prepared as a colloid, or other conventionaltechniques may be employed which provide an extended serum half-life. Avariety of methods are available for preparing liposomes, as describedin, e.g., Szoka et al., Ann. Rev. Biophys. Bioeng. 9:467 (1980), U.S.Pat. Nos. 4,235,871, 4,501,728 and 4,837,028. The preparations may alsobe provided in controlled release or slow-release forms for release andadministration of the polysialic acid derivative compositions as amixture or in serial fashion.

A liquid composition will generally be composed of a suspension orsolution of the compound or pharmaceutically acceptable salt in asuitable liquid carrier(s), for example, ethanol, glycerine, sorbitol,non-aqueous solvent such as polyethylene glycol, oils or water, with asuspending agent, preservative, surfactant, wetting agent, flavoring orcoloring agent. Alternatively, a liquid formulation can be prepared froma reconstitutable powder.

The compounds of the present disclosure and their pharmaceuticallyacceptable salts that are active when given parenterally can beformulated for intramuscular, intrathecal, or intravenousadministration. A typical composition for intramuscular or intrathecaladministration will be of a suspension or solution of active ingredientin an oil, for example, arachis oil or sesame oil. A typical compositionfor intravenous or intrathecal administration will be a sterile isotonicaqueous solution containing, for example, active ingredient and dextroseor sodium chloride, or a mixture of dextrose and sodium chloride. Otherexamples are lactated Ringer's injection, lactated Ringer's plusdextrose injection, Normosol-M and dextrose, Isolyte E, acylatedRinger's injection, and the like. Optionally, a co-solvent, for example,polyethylene glycol, a chelating agent, for example, ethylenediaminetetracetic acid, and an anti-oxidant, for example, sodium metabisulphitemay be included in the formulation. Alternatively, the solution can befreeze dried and then reconstituted with a suitable solvent just priorto administration.

The compounds of the present disclosure and their pharmaceuticallyacceptable salts which are active on rectal administration can beformulated as suppositories. A typical suppository formulation willgenerally consist of active ingredient with a binding and/or lubricatingagent such as a gelatin or cocoa butter or other low melting vegetableor synthetic wax or fat.

The compounds of the present disclosure and their pharmaceuticallyacceptable salts which are active on topical administration can beformulated as transdermal compositions or transdermal delivery devices(“patches”). Such compositions include, for example, a backing, activecompound reservoir, a control membrane, liner and contact adhesive. Suchtransdermal patches may be used to provide continuous or discontinuousinfusion of the compounds of the present disclosure in controlledamounts. The construction and use of transdermal patches for thedelivery of pharmaceutical agents is well known in the art. See, e.g.,U.S. Pat. No. 5,023,252, herein incorporated by reference in itsentirety. Such patches may be constructed for continuous, pulsatile, oron demand delivery of pharmaceutical agents.

In certain embodiments of interest, the polysialic acid derivativecomposition is administered as a single pharmaceutical formulation. Italso may be administered with an effective amount of another agent thatincludes other suitable compounds and carriers, and also may be used incombination with other active agents. The present disclosure, therefore,also includes pharmaceutical compositions comprising pharmaceuticallyacceptable excipients. The pharmaceutically acceptable excipientsinclude, for example, any suitable vehicles, adjuvants, carriers ordiluents, and are readily available to the public. The pharmaceuticalcompositions of the present disclosure may further contain other activeagents as are well known in the art.

One skilled in the art will appreciate that a variety of suitablemethods of administering a formulation of the present disclosure to asubject or host, e.g., patient, in need thereof, are available, and,although more than one route can be used to administer a particularformulation, a particular route can provide a more immediate and moreeffective reaction than another route. Pharmaceutically acceptableexcipients are also well-known to those who are skilled in the art, andare readily available. The choice of excipient will be determined inpart by the particular compound, as well as by the particular methodused to administer the composition. Accordingly, there is a wide varietyof suitable formulations of the pharmaceutical composition of thepresent disclosure. The following methods and excipients are merelyexemplary and are in no way limiting.

The formulations of the present disclosure can be made into aerosolformulations to be administered via inhalation. These aerosolformulations can be placed into pressurized acceptable propellants, suchas dichlorodifluoromethane, propane, nitrogen, and the like. They mayalso be formulated as pharmaceuticals for non-pressured preparationssuch as for use in a nebulizer or an atomizer.

Formulations suitable for parenteral administration include aqueous andnon-aqueous, isotonic sterile injection solutions, which can containanti-oxidants, buffers, bacteriostats, and solutes that render theformulation isotonic with the blood of the intended recipient, andaqueous and non-aqueous sterile suspensions that can include suspendingagents, solubilizers, thickening agents, stabilizers, and preservatives.The formulations can be presented in unit-dose or multi-dose sealedcontainers, such as ampules and vials, and can be stored in afreeze-dried (lyophilized) condition requiring only the addition of thesterile liquid excipient, for example, water, for injections,immediately prior to use. Extemporaneous injection solutions andsuspensions can be prepared from sterile powders, granules, and tabletsof the kind previously described.

Formulations suitable for topical administration may be presented ascreams, gels, pastes, or foams, containing, in addition to the activeingredient, such carriers as are known in the art to be appropriate.

Suppository formulations are also provided by mixing with a variety ofbases such as emulsifying bases or water-soluble bases. Formulationssuitable for vaginal administration may be presented as pessaries,tampons, creams, gels, pastes, foams.

Unit dosage forms for oral or rectal administration such as syrups,elixirs, and suspensions may be provided wherein each dosage unit, forexample, teaspoonful, tablespoonful, tablet or suppository, contains apredetermined amount of the composition containing one or morepolysialic acid derivatives. Similarly, unit dosage forms for injectionor intravenous administration may comprise the polysialic acidderivative (s) in a composition as a solution in sterile water, normalsaline or another pharmaceutically acceptable carrier.

The term “unit dosage form,” as used herein, refers to physicallydiscrete units suitable as unitary dosages for human and animalsubjects, each unit containing a predetermined quantity of compounds ofthe present disclosure calculated in an amount sufficient to produce thedesired effect in association with a pharmaceutically acceptablediluent, carrier or vehicle. The specifications for the novel unitdosage forms of the present disclosure depend on the particular compoundemployed and the effect to be achieved, and the pharmacodynamicsassociated with each compound in the host.

Those of skill in the art will readily appreciate that dose levels canvary as a function of the specific compound, the nature of the deliveryvehicle, and the like. Suitable dosages for a given compound are readilydeterminable by those of skill in the art by a variety of means.

Optionally, the pharmaceutical composition may contain otherpharmaceutically acceptable components, such a buffers, surfactants,antioxidants, viscosity modifying agents, preservatives and the like.Each of these components is well-known in the art. See, e.g., U.S. Pat.No. 5,985,310, the disclosure of which is herein incorporated byreference.

Other components suitable for use in the formulations can be found inRemington's Pharmaceutical Sciences, Mack Pub. Co., 18th edition (June1995). In an embodiment, the aqueous cyclodextrin solution furthercomprise dextrose, e.g., about 5% dextrose.

UTILITY Exemplary Applications & Related Embodiments

The compounds and methods disclosed herein find use in a variety ofapplications, where in many applications the methods are modulating atleast one cellular function, such as increased expression of theantigen/polysialic acid derivative on the surface of a cell, or aremodulating an immune response, such in immunization of a subject toelicit antibodies that bind a deNAc SA epitope such as may be borne on acancerous or bacterial cell (e.g., Neisseria or E. coli K1).

In the context of modulating at least one cellular function as well asin the context of eliciting anti-cancer cell antibodies, the methods andcompositions disclosed herein find use in treating cellularproliferation disorders. Thus, a representative therapeutic applicationis the treatment of cellular proliferative disease conditions ingeneral, e.g., cancers and related conditions characterized by abnormalcellular proliferation concomitant. Such disease conditions includecancer/neoplastic diseases and other diseases characterized by thepresence of unwanted cellular proliferation, e.g., hyperplasias, and thelike. As indicated, cellular proliferation disorders include those thatabnormally express the deNAc SA epitope, which can be determined usinganti-deNAc SA antibody or derivatives thereof.

In the context of modulating an immune response to elicit anti-bacterialantibodies, the methods and compositions disclosed herein find use ineliciting immunoprotective and/or immunotherapeutic immune responseagainst bacteria that bear a deNAc SA, as in capsular polysaccharide ofa deNAc SA epitope-bearing Neisseria (e.g., N. meningitidis, e.g., N.meningitidis Group B) or E. coli K1. In this context the polysialic acidderivative is administered in a form that provides for eliciting anantibody response, e.g., administered in an immunogenic amount,administered in conjunction with an adjuvant, and/or administered as aconjugate with a carrier peptide or protein.

Of particular interest are antibodies that have antigen bindingspecificity for the polysialic acid derivatives described herein or theantigen binding specificity of mAb SEAM 3. Of particular interest areantibodies that specifically bind a deNAc SA epitope with little or nodetectable binding to human polysialic acid. Examples of such antibodiesinclude those having a light chain polypeptide comprising CDR1, CDR2 andCDR3 of the variable region of a SEAM 3 light chain polypeptide and aheavy chain polypeptide comprising CDR1, CDR2, and CDR3 of the variableregion of the heavy chain polypeptide. Such antibodies include chimericantibodies, humanized antibodies, and the like.

By “treatment” is meant that at least an amelioration of the symptomsassociated with the condition afflicting the host is achieved, whereamelioration is used in a broad sense to refer to at least a reductionin the magnitude of a parameter, e.g. symptom, associated with thecondition being treated. As such, treatment also includes situationswhere the pathological condition, or at least symptoms associatedtherewith, are completely inhibited, e.g., prevented from happening, orstopped, e.g. terminated, such that the host no longer suffers from thecondition, or at least the symptoms that characterize the condition.Thus treatment includes: (i) prevention, that is, reducing the risk ofdevelopment of clinical symptoms, including causing the clinicalsymptoms not to develop, e.g., preventing disease progression to aharmful state; (ii) inhibition, that is, arresting the development orfurther development of clinical symptoms, e.g., mitigating or completelyinhibiting an active disease, e.g., so as to decrease tumor load, whichdecrease can include elimination of detectable cancerous cells; and/or(iii) relief, that is, causing the regression of clinical symptoms.

A variety of hosts are treatable according to the methods disclosedherein. Generally such hosts are “mammals” or “mammalian,” where theseterms are used broadly to describe organisms which are within the classmammalia, including the orders carnivore (e.g., dogs and cats), rodentia(e.g., mice, guinea pigs, and rats), and primates (e.g., humans,chimpanzees, and monkeys). In many embodiments, the hosts will behumans. In the context of anti-bacterial vaccination methods, ofinterest are hosts that are susceptible to disease that can be caused byinfection by a deNAc SA epitope-bearing bacteria, such as Neisseria(e.g., N. meningitidis, e.g., N. meningitidis Group B) or E. coli K1.

The methods disclosed herein can find use in, among other applications,the treatment of cellular proliferative disease conditions in which aneffective amount of the polysialic acid derivative composition isadministered to the subject in need thereof. Treatment is used broadlyas defined above, e.g., to include prevention or at least anamelioration in one or more of the symptoms of the disease, as well as acomplete cessation thereof, as well as a reversal and/or completeremoval of the disease condition, e.g., cure.

Compositions of the present disclosure can comprise a therapeuticallyeffective amount of a polysialic acid derivative composition, as well asany other compatible components, as needed. By “therapeuticallyeffective amount” is meant that the administration of that amount to anindividual, either in a single dose, as part of a series of the same ordifferent polysialic acid derivative compositions, is effective toenhance de-N-acetyl sialic acid antigen of a cancer cell and/or elicitan anti-de-N-acetyl sialic acid antigen antibody response, particularlyone effective to inhibit the growth of a cancerous cell in a subject.Such therapeutically effective amount of polysialic acid derivativecomposition and/or anti-polysialic acid derivative antibodies includescooperative and/or synergistic inhibition of cell growth in conjunctionwith one or more other therapies (e.g., immunotherapy, chemotherapy,radiation therapy etc.). As noted below, the therapeutically effectiveamount can be adjusted in connection with dosing regimen and diagnosticanalysis of the subject's condition (e.g., monitoring for the present orabsence of a cell surface epitopes using a SEAM 3 antibody or antibodyspecific for an polysialic acid derivative) and the like.

As discussed above, the amount administered to an animal, particularly ahuman, in the context of the methods disclosed herein should besufficient to affect a prophylactic or therapeutic response in theanimal over a reasonable time frame, and varies depending upon the goalof the administration, the health and physical condition of theindividual to be treated, age, the taxonomic group of individual to betreated (e.g., human, non-human primate, primate, etc.), the degree ofresolution desired, the formulation of the polysialic acid derivativecomposition, the treating clinician's assessment of the medicalsituation, and other relevant factors. One skilled in the art will alsorecognize that dosage will depend on a variety of factors including thestrength of the particular compound employed, the condition of theanimal, and the body weight of the animal, as well as the severity ofthe illness and the stage of the disease. The size of the dose will alsobe determined by the existence, nature, and extent of any adverseside-effects that might accompany the administration of a particularcompound. Thus it is expected that the amount will fall in a relativelybroad range, but can nevertheless be routinely determined throughvarious features of the subject such as note above.

The polysialic acid derivative compositions (which may be optionallyconjugated) can be used alone or in combination with other therapies(e.g., antibacterial agents, other anti-cancer agents, and the like).When used in combination, the various compositions can be provided inthe same or different formulations. Where administered in differentformulations, the compositions can be administered at the same ordifferent dosage regimen (e.g., by the same or different routes, at thesame or different time (e.g., on the same or different days)), and thelike). In general, administration of the polysialic acid derivativecomposition can be performed serially, at the same time, or as amixture, as described in more detail below. Administration can beserial, with repeated doses of polysialic acid derivative composition.Exemplary dosage regimens are described below in more detail.

The compositions also can be administered to subject that is at risk ofdisease to prevent or at least partially arrest the development ofdisease and its complications. A subject is “at risk” where, forexample, the subject exhibits one or more signs or symptoms of disease,but which are insufficient for certain diagnosis and/or who has been ormay be exposed to conditions that increase the probability of disease.For example, the polysialic acid derivative compositions can also beadministered to subject that is at risk of a cancer, has a cancer, or isat risk of metastasis of a cancer having a cell surface deNAc SA epitope(e.g., a cell surface ganglioside that is at least partiallyde-N-acetylated).

Polysialic acid derivative compositions can be administered serially oroverlapping to maintain a therapeutically effective amount as believedneeded for the desired end result (e.g., enhancing de-N-acetyl sialicacid antigen of a cancer cell, inhibition of cancerous cell growththrough antibody binding and/or production). Typically, each dose andthe timing of its administration is generally provided in an amount thatis tolerated by the health of the subject, and can be based on IC50and/or the EC50 as noted above. Thus amounts can vary widely for a giventreatment.

Therapeutic response to the dose or treatment regime may be determinedby known methods (e.g. by assessing an increase in de-N-acetyl sialicacid antigen presentation by a cell; by obtaining serum from theindividual before and after the initial immunization, and demonstratinga change in anti-de-N-acetyl sialic acid antigen antibodies; or thelike). The dosing may include washout periods to allow for clearance ofthe initial material, followed by halting or resumption of treatment.Thus dosage strategies can be modified accordingly.

In one embodiment, the polysialic acid derivative composition isadministered at least once, usually at least twice, and in someembodiments more than twice. In a related embodiment, the polysialicacid derivative composition is administered in combination along adosing schedule and course in conjunction with chemotherapy. In anotherembodiment, the polysialic acid derivative composition is administeredin combination with a dosing schedule and course in conjunction withimmunotherapy. In yet another embodiment, the polysialic acid derivativecomposition is administered in combination with a dosing schedule andcourse in conjunction with radiation therapy. Each individual dose ofthe polysialic acid derivative composition may be administered before,during or after the complementary therapy such as immunotherapy,chemotherapy, or radiation therapy. As can be appreciated, combinationtherapies using a polysialic acid derivative composition may be adjustedfor a given end need.

Exemplary Cancer Therapies

The polysialic acid derivative compositions find use in a variety ofcancer therapies (including cancer prevention and post-diagnosis cancertherapy) in a mammalian subject, particularly in a human. Subjectshaving, suspected of having or at risk of developing a tumor arecontemplated for therapy and diagnosis described herein. Samplesobtained from such subject are likewise suitable for use in the methodsof the present disclosure.

More particularly, polysialic acid derivative compositions describedherein can be administered to a subject (e.g. a human patient) to, forexample, facilitate an increase in de-N-acetyl sialic acid antigen of acancer cell, e.g., an increase in total de-N-acetyl sialic acid antigen,which may be present on a cell surface, e.g., as during cell division.This can be accomplished by administering a polysialic acid derivativeto the subject as described herein so as to provide for an increase inde-N-acetyl sialic acid antigen in a cancer cell as compared to prior tosuch administering.

In the context of cancer therapies, as well as other therapies in whichit is desirable to increase de-N-acetyl sialic acid antigen of a cell,it may be desirable to avoid administration of polysialic acidderivative in a manner that would elicit anti-polysialic acid derivativeantibodies. Thus, in some embodiments it may be desirable to administerpolysialic acid derivative in a compositions that does not contain anadjuvant and/or to administer the polysialic acid derivativenon-immunogenic form.

The increased de-N-acetyl sialic acid antigen of the cell can beexploited in therapy using anti-de-N-acetyl sialic acid antigen antibodythat is cytotoxic to the cell (e.g., as a result of properties of theantibody per se (e.g., as in induction of apoptosis of the cell byantibody binding) and/or by delivery of a cytotoxin conjugated to theantibody. For example, by increasing de-N-acetyl sialic acid antigen ofthe cell, the cell can be enhanced for anti-de-N-acetyl sialic acidantigen antibody binding (e.g., SEAM 3 binding), thus enhancingantibody-mediated cancer cell therapy (e.g., as a result of increaseddelivery of cytotoxic antibodies to the cancer cell. Such therapies canbe useful in cancer therapy to, for example, reduce tumor size, reducetumor load, and/or improve the clinical outcome in patients.

The polysialic acid derivative compositions thus may be advantageouslyused in an anti-cancer therapy, particularly where the cancerous cellspresent a deNAc SA epitope on an extracellularly accessible cell surface(e.g., a deNAc SA epitope on an at least partially de-N-acetylatedganglioside or other glycoconjugate). In one embodiment, the cancer isone that presents a SEAM 3-reactive antigen. Cancers that present a SEAM3-reactive antigen can be identified by methods known in the art.Exemplary methods of detection and diagnosis are described below.

In some embodiments, the anti-cancer therapy can be particularlydirected to dividing (replicating, proliferating) cancerous cells. Asshown in the Examples below, antibody raised against polysialic acidderivatives were particularly effective against cancerous cells bearingthe epitope specifically bound by SEAM 3 antibody. Also, the level ofextracellularly accessible antigen bound by SEAM 3 is increased duringcell division as compared to non-dividing cells, and binding of SEAM3drives the cell toward anaphase (into pre-GO). Since most cancers aremore rapidly dividing than normal cells of the same type, cells thatpossess a SEAM 3-reactive antigen are attractive for polysialic acidderivative-based cancer therapy. Also, the antibodies identified hereinto the polysialic acid derivatives of the present disclosure can exhibitenhanced binding as compared to SEAM 3, and thus may have clinicalbenefits that may be greater than SEAM 3.

Thus the present disclosure particularly provides anti-cancer therapydirected toward cancerous cells involving administration of polysialicacid derivative compositions having an epitope recognized by a SEAM 3mAb. Cancers particularly amenable to polysialic acid derivative therapycan be identified by examining markers of cellular proliferation (e.g.,Ki-67 antigen) and/or by examining the presence/accessibility of thedeNAc SA epitope bound by SEAM 3 in dividing cells or by the antibodiesspecific for the polysialic acid derivatives of the present disclosure(e.g., as in an in vitro assay).

Cancers having a cell surface-accessible deNAc SA epitope include thosehaving an at least partially de-N-acetylated ganglioside and/or aprotein having a sialic acid modification that contains a deNAc SAepitope. Cancers having de-N-acetylated gangliosides have beendescribed.

The presence of de-N-acetyl sialic acid residues in normal human tissueappears to be transient and very low abundance, being found only in afew blood vessels, infiltrating mononuclear cells in the skin and colon,and at moderate levels in skin melanocytes. It is prevalent only inabnormal cells, such as melanomas, leukemias and lymphomas. Sinceexpression of high levels of deNAc SA antigens (e.g., de-N-acetylgangliosides) occurs predominantly in cancer cells, treatment withpolysialic acid derivative compositions can be used to inducecytotoxicity, and can block tumor growth. In addition, polysialic acidderivative compositions can be used therapeutically to effect/preventadhesion and invasion of cancer cells in other tissues. For example,expression of SEAM 3-reactive antigens can be detected in very lowlevels in normal tissue includes epithelial cells of skin, bladder(urothelial), kidney (tubular epithelial), stomach glandular epithelium,lung macrophages, peripheral nerve endothelium and weak staining ofskeletal muscle. In contrast, SEAM 3-reactive antigen can be detected atsignificantly higher levels in tumors, in addition to those above, suchas nephroblastoma, and adenocarcinomas of the stomach, uterus, andovaries.

Exemplary cancers presenting a deNAc SA epitope include cancer cellspresenting a de-N-acetyl ganglioside containing a de-N-acetyl sialicacid residue (e.g. GM2alpha, GM1alpha, GD1beta, GM1b, GD1c, GD1alpha,GM3, GM2, GM1, GD13, GT13, GT1halpha, GD3, GD2, GD1b, GT1b, GQ1b,Gomega1halpha, GT3, GT2, GT1c, GQ1c, and GP1c). Of particular interestare gangliosides that contain two or more sialic acid residues linked byalpha 2-8 glycosidic bonds (e.g., GD1c, GT13, GD3, GD1b, GT1b, GQ1b,Gomega1halpha, GT3, GT1c, GQ1c, and GP1c) in which at least one residueis de-N-acetylated. In some embodiments, the ganglioside that containstwo or more sialic acid residues linked by alpha 2-8 glycosidic bonds isa ganglioside other than GD3 and/or other than GM3. In some embodiments,the target of the cancer is a deNAc SA epitope other than one present ona de-N-acetylated ganglioside (e.g., a de-N-acetylated residue of asialic acid-modified protein).

In one embodiment polysialic acid derivative compositions can be used totreat cancers that present a SEAM 3 reactive antigen on a cell surface,including cancers that exhibit an extracellularly accessible SEAM3-reactive antigen during cell division.

In another embodiment polysialic acid derivative compositions can beused to treat cancers that present deNAc SA epitope on a cell surface,including cancers that exhibit an extracellularly accessible reactiveantigen during cell rest.

It should be noted that while deNAc SA epitopes and/or SEAM 3-reactiveantigens may be expressed at higher levels on a cancer cell compared toa non-cancerous cell, this is not a limitation of the therapiesdisclosed herein. For example, where the cancer involves a cell typethat can be replenished (e.g., B cell, T cell, or other cell ofhematopoietic origin, as in leukemias and lymphomas), inhibition ofnormal cell growth can be acceptable since damage to a subject bydepleting such cells can be treated (e.g., with drugs to stimulaterepopulation of normal cells, e.g., GM-CSF, EPO, and the like).

The methods relating to cancer contemplated herein include, for example,use of polysialic acid derivative therapy alone or in combination withdeNAc SA antigens as a anti-cancer vaccine or therapy, as well as use ofantibodies generated using deNAc SA antigens in anti-cancer vaccines(e.g., by passive immunization) or therapies. The methods are useful inthe context of treating or preventing a wide variety of cancers,including carcinomas, sarcomas, leukemias, and lymphomas.

Carcinomas that can be amenable to therapy by a method disclosed hereininclude, but are not limited to, esophageal carcinoma, hepatocellularcarcinoma, basal cell carcinoma (a form of skin cancer), squamous cellcarcinoma (various tissues), bladder carcinoma, including transitionalcell carcinoma (a malignant neoplasm of the bladder), bronchogeniccarcinoma, colon carcinoma, colorectal carcinoma, gastric carcinoma,lung carcinoma, including small cell carcinoma and non-small cellcarcinoma of the lung, adrenocortical carcinoma, thyroid carcinoma,pancreatic carcinoma, breast carcinoma, ovarian carcinoma, prostatecarcinoma, adenocarcinoma, sweat gland carcinoma, sebaceous glandcarcinoma, papillary carcinoma, papillary adenocarcinoma,cystadenocarcinoma, medullary carcinoma, renal cell carcinoma, ductalcarcinoma in situ or bile duct carcinoma, choriocarcinoma, seminoma,embryonal carcinoma, Wilm's tumor, cervical carcinoma, uterinecarcinoma, testicular carcinoma, osteogenic carcinoma, epithelialcarcinoma, and nasopharyngeal carcinoma.

Sarcomas that can be amenable to therapy by a method disclosed hereininclude, but are not limited to, fibrosarcoma, myxosarcoma, liposarcoma,chondrosarcoma, chordoma, osteogenic sarcoma, osteosarcoma,angiosarcoma, endotheliosarcoma, lymphangiosarcoma,lymphangioendotheliosarcoma, synovioma, mesothelioma, Ewing's sarcoma,leiomyosarcoma, rhabdomyosarcoma, and other soft tissue sarcomas.

Other solid tumors that can be amenable to therapy by a method disclosedherein include, but are not limited to, glioma, astrocytoma,medulloblastoma, craniopharyngioma, ependymoma, pinealoma,hemangioblastoma, acoustic neuroma, oligodendroglioma, menangioma,melanoma, neuroblastoma, and retinoblastoma.

Leukemias that can be amenable to therapy by a method disclosed hereininclude, but are not limited to, a) chronic myeloproliferative syndromes(neoplastic disorders of multipotential hematopoietic stem cells); b)acute myelogenous leukemias (neoplastic transformation of amultipotential hematopoietic stem cell or a hematopoietic cell ofrestricted lineage potential; c) chronic lymphocytic leukemias (CLL;clonal proliferation of immunologically immature and functionallyincompetent small lymphocytes), including B-cell CLL, T-cell CLLprolymphocytic leukemia, and hairy cell leukemia; and d) acutelymphoblastic leukemias (characterized by accumulation of lymphoblasts).Lymphomas that can be treated according to the treatment methodsdisclosed herein include, but are not limited to, B-cell lymphomas(e.g., Burkitt's lymphoma); Hodgkin's lymphoma; non-Hodgkin's lymphoma,and the like.

Other cancers that can be amenable to treatment according to the methodsdisclosed herein include atypical meningioma (brain), islet cellcarcinoma (pancreas), medullary carcinoma (thyroid), mesenchymoma(intestine), hepatocellular carcinoma (liver), hepatoblastoma (liver),clear cell carcinoma (kidney), and neurofibroma mediastinum.

Further exemplary cancers that can be amenable to treatment using amethods disclosed herein include, but are not limited to, cancers ofneuroectodermal and epithelial origin. Examples of cancers ofneuroectodermal origin include, but are not limited to, Ewings sarcoma,spinal tumors, brain tumors, supratenbrial primative neuroectodermaltumors of infancy, tubulocystic carcinoma, mucinous tubular and spindlecell carcinoma, renal tumors, mediastinum tumors, neurogliomas,neuroblastomas, and sarcomas in adolescents and young adults. Examplesof epithelial origin include, but are not limited to, small cell lungcancer, cancers of the breast, eye lens, colon, pancreas, kidney, liver,ovary, and bronchial epithelium. In some embodiments, the treatmentmethods disclosed herein do not include treatment of melanoma (i.e., thecancer is other than melanoma). In other embodiments, the treatmentmethods disclosed herein do not include treatment of lymphoma (i.e., thecancer is other than lymphoma). In certain embodiments, the methods ofthe present disclosure are used to treat cancer cells known to expressde-N-acetyl gangliosides include melanomas and some lymphomas. As notedabove, cancers that overexpress the precursor gangliosides GM3 and GD3are likely to also express the greatest amount of de-N-acetylgangliosides on the cell surface.

Combinations with Other Cancer Therapies

Therapeutic administration of the polysialic acid derivativecompositions can include administration as a part of a therapeuticregimen that may or may not be in conjunction with additional standardanti-cancer therapeutics, including but not limited to immunotherapy,chemotherapeutic agents and surgery (e.g., as those described furtherbelow).

In addition, therapeutic administration of the polysialic acidderivative compositions can also be post-therapeutic treatment of thesubject with an anti-cancer therapy, where the anti-cancer therapy canbe, for example, surgery, radiation therapy, administration ofchemotherapeutic agents, and the like. Use of monoclonal antibodies,particularly monoclonal antibodies that can provide forcomplement-mediated killing, and/or antibody-dependent cellularcytotoxicity-mediated killing, of a target cell are of particularinterest (e.g., treatment with an anti-deNAc SA epitope antibody (e.g.,SEAM 3 or an antibody specific for an polysialic acid derivative of thepresent disclosure) after identification of a primary tumor composed ofcells expressing a deNAc SA epitope (e.g., a de-N-acetyl ganglioside)).Cancer therapy using polysialic acid derivative compositions of thepresent disclosure in combination with immunotherapy that employs PSAantigen/anti-deNAc SA epitope antibodies is of particular interest (U.S.Ser. No. 11/645,255 and PCT Application No. US2006/048850; incorporatedherein by reference).

For example, the polysialic acid derivative compositions can beadministered in combination with one or more chemotherapeutic agents(e.g., cyclophosphamide, doxorubicin, vincristine and prednisone(CHOP)), and/or in combination with radiation treatment and/or incombination with surgical intervention (e.g., pre- or post-surgery toremove a tumor). Where the polysialic acid derivative is used inconnection with surgical intervention, the polysialic acid derivativecompositions can be administered prior to, at the time of, or aftersurgery to remove cancerous cells, and may be administered systemicallyor locally at the surgical site. The polysialic acid derivativecompositions alone or in combinations described above can beadministered systemically (e.g., by parenteral administration, e.g., byan intravenous route) or locally (e.g., at a local tumor site, e.g., byintratumoral administration (e.g., into a solid tumor, into an involvedlymph node in a lymphoma or leukemia), administration into a bloodvessel supplying a solid tumor, etc.).

Any of a wide variety of cancer therapies can be used in combinationwith the polysialic acid derivative-based therapies described herein.Such cancer therapies include surgery (e.g., surgical removal ofcancerous tissue), radiation therapy, bone marrow transplantation,chemotherapeutic treatment, biological response modifier treatment, andcertain combinations of the foregoing.

Radiation therapy includes, but is not limited to, X-rays or gamma raysthat are delivered from either an externally applied source such as abeam, or by implantation of small radioactive sources.

Chemotherapeutic agents are non-peptidic (i.e., non-proteinaceous)compounds that reduce proliferation of cancer cells, and encompasscytotoxic agents and cytostatic agents. Non-limiting examples ofchemotherapeutic agents include alkylating agents, nitrosoureas,antimetabolites, antitumor antibiotics, plant (vinca) alkaloids, andsteroid hormones.

Agents that act to reduce cellular proliferation are known in the artand widely used. Such agents include alkylating agents, such as nitrogenmustards, nitrosoureas, ethylenimine derivatives, alkyl sulfonates, andtriazenes, including, but not limited to, mechlorethamine,cyclophosphamide (CYTOXAN™), melphalan (L-sarcolysin), carmustine(BCNU), lomustine (CCNU), semustine (methyl-CCNU), streptozocin,chlorozotocin, uracil mustard, chlormethine, ifosfamide, chlorambucil,pipobroman, triethylenemelamine, triethylenethiophosphoramine, busulfan,dacarbazine, and temozolomide.

Antimetabolite agents include folic acid analogs, pyrimidine analogs,purine analogs, and adenosine deaminase inhibitors, including, but notlimited to, cytarabine (CYTOSAR-U), cytosine arabinoside, fluorouracil(5-FU), floxuridine (FudR), 6-thioguanine, 6-mercaptopurine (6-MP),pentostatin, 5-fluorouracil (5-FU), methotrexate,10-propargyl-5,8-dideazafolate (PDDF, CB3717),5,8-dideazatetrahydrofolic acid (DDATHF), leucovorin, fludarabinephosphate, pentostatine, and gemcitabine.

Suitable natural products and their derivatives, (e.g., vinca alkaloids,antitumor antibiotics, enzymes, lymphokines, and epipodophyllotoxins),include, but are not limited to, Ara-C, paclitaxel (TAXOL®), docetaxel(TAXOTERE®), deoxycoformycin, mitomycin-C, L-asparaginase, azathioprine;brequinar; alkaloids, e.g. vincristine, vinblastine, vinorelbine,vindesine, etc.; podophyllotoxins, e.g. etoposide, teniposide, etc.;antibiotics, e.g. anthracycline, daunorubicin hydrochloride (daunomycin,rubidomycin, cerubidine), idarubicin, doxorubicin, epirubicin andmorpholino derivatives, etc.; phenoxizone biscyclopeptides, e.g.dactinomycin; basic glycopeptides, e.g. bleomycin; anthraquinoneglycosides, e.g. plicamycin (mithramycin); anthracenediones, e.g.mitoxantrone; azirinopyrrolo indolediones, e.g. mitomycin; macrocyclicimmunosuppressants, e.g. cyclosporine, FK-506 (tacrolimus, prograf),rapamycin, etc.; and the like.

Other anti-proliferative cytotoxic agents are navelbene, CPT-11,anastrazole, letrazole, capecitabine, reloxafine, cyclophosphamide,ifosamide, and droloxafine.

Microtubule affecting agents that have antiproliferative activity arealso suitable for use and include, but are not limited to,allocolchicine (NSC 406042), Halichondrin B (NSC 609395), colchicine(NSC 757), colchicine derivatives (e.g., NSC 33410), dolstatin 10 (NSC376128), maytansine (NSC 153858), rhizoxin (NSC 332598), paclitaxel(TAXOL®), TAXOL® derivatives, docetaxel (TAXOTERE®), thiocolchicine (NSC361792), trityl cysterin, vinblastine sulfate, vincristine sulfate,natural and synthetic epothilones including but not limited to,eopthilone A, epothilone B, discodermolide; estramustine, nocodazole,and the like.

Hormone modulators and steroids (including synthetic analogs) that aresuitable for use include, but are not limited to, adrenocorticosteroids,e.g. prednisone, dexamethasone, etc.; estrogens and pregestins, e.g.hydroxyprogesterone caproate, medroxyprogesterone acetate, megestrolacetate, estradiol, clomiphene, tamoxifen; etc.; and adrenocorticalsuppressants, e.g. aminoglutethimide; 17α-ethinylestradiol;diethylstilbestrol, testosterone, fluoxymesterone, dromostanolonepropionate, testolactone, methylprednisolone, methyl-testosterone,prednisolone, triamcinolone, chlorotrianisene, hydroxyprogesterone,aminoglutethimide, estramustine, medroxyprogesterone acetate,leuprolide, Flutamide (Drogenil), Toremifene (Fareston), and ZOLADEX®.Estrogens stimulate proliferation and differentiation, thereforecompounds that bind to the estrogen receptor are used to block thisactivity. Corticosteroids may inhibit T cell proliferation.

Other chemotherapeutic agents include metal complexes, e.g. cisplatin(cis-DDP), carboplatin, etc.; ureas, e.g. hydroxyurea; and hydrazines,e.g. N-methylhydrazine; epidophyllotoxin; a topoisomerase inhibitor;procarbazine; mitoxantrone; leucovorin; tegafur; etc. Otheranti-proliferative agents of interest include immunosuppressants, e.g.mycophenolic acid, thalidomide, desoxyspergualin, azasporine,leflunomide, mizoribine, azaspirane (SKF 105685); IRESSA® (ZD 1839,4-(3-chloro-4-fluorophenylamino)-7-methoxy-6-(3-(4-morpholinyl)propoxy)quinazoline);etc.

“Taxanes” include paclitaxel, as well as any active taxane derivative orpro-drug. “Paclitaxel” (which should be understood herein to includeanalogues, formulations, and derivatives such as, for example,docetaxel, TAXOL, TAXOTERE (a formulation of docetaxel), 10-desacetylanalogs of paclitaxel and 3′N-desbenzoyl-3′N-t-butoxycarbonyl analogs ofpaclitaxel) may be readily prepared utilizing techniques known to thoseskilled in the art (see also WO 94/07882, WO 94/07881, WO 94/07880, WO94/07876, WO 93/23555, WO 93/10076; U.S. Pat. Nos. 5,294,637; 5,283,253;5,279,949; 5,274,137; 5,202,448; 5,200,534; 5,229,529; and EP 590,267),or obtained from a variety of commercial sources, including for example,Sigma Chemical Co., St. Louis, Mo. (T7402 from Taxus brevifolia; orT-1912 from Taxus yannanensis).

Paclitaxel should be understood to refer to not only the commonchemically available form of paclitaxel, but analogs and derivatives(e.g., TAXOTERE™ docetaxel, as noted above) and paclitaxel conjugates(e.g., paclitaxel-PEG, paclitaxel-dextran, or paclitaxel-xylose).

Also included within the term “taxane” are a variety of knownderivatives, including both hydrophilic derivatives, and hydrophobicderivatives. Taxane derivatives include, but not limited to, galactoseand mannose derivatives described in International Patent ApplicationNo. WO 99/18113; piperazino and other derivatives described in WO99/14209; taxane derivatives described in WO 99/09021, WO 98/22451, andU.S. Pat. No. 5,869,680; 6-thio derivatives described in WO 98/28288;sulfenamide derivatives described in U.S. Pat. No. 5,821,263; and taxolderivative described in U.S. Pat. No. 5,415,869. It further includesprodrugs of paclitaxel including, but not limited to, those described inWO 98/58927; WO 98/13059; and U.S. Pat. No. 5,824,701.

In the treatment of some individuals with the compounds of the presentpresent disclosure, it may be desirable to use a high dose regimen inconjunction with a rescue agent for non-malignant cells. In suchtreatment, any agent capable of rescue of non-malignant cells can beemployed, such as citrovorum factor, folate derivatives, or leucovorin.Such rescue agents are well known to those of ordinary skill in the art.Rescue agents include those which do not interfere with the ability ofthe present inventive compounds to modulate cellular function.

Particular applications in which the methods and compositions disclosedherein find use include those described in U.S. Pat. Nos. 2,512,572;3,892,801; 3,989,703; 4,057,548; 4,067,867; 4,079,056; 4,080,325;4,136,101; 4,224,446; 4,306,064; 4,374,987; 4,421,913; 4,767,859;3,981,983; 4,043,759; 4,093,607; 4,279,992; 4,376,767; 4,401,592;4,489,065; 4,622,218; 4,625,014; 4,638,045; 4,671,958; 4,699,784;4,785,080; 4,816,395; 4,886,780; 4,918,165; 4,925,662; 4,939,240;4,983,586; 4,997,913; 5,024,998; 5,028,697; 5,030,719; 5,057,313;5,059,413; 5,082,928; 5,106,950; 5,108,987; 4,106,488; 4,558,690;4,662,359; 4,396,601; 4,497,796; 5,043,270; 5,166,149; 5,292,731;5,354,753; 5,382,582; 5,698,556; 5,728,692; and 5,958,928; thedisclosures of which are herein incorporated by reference.

Production of Anti-Polysialic Acid Derivative Antibody Response

Polysialic acid derivatives, including conjugates thereof, as describedherein can be used in eliciting an anti-bacterial antibody response, aswell as in eliciting an anti-cancer cell antibody response. In generalimmunization is accomplished by administration by any suitable route,including administration of the composition orally, nasally,nasopharyngeally, parenterally, enterically, gastrically, topically,transdermally, subcutaneously, intramuscularly, in tablet, solid,powdered, liquid, aerosol form, locally or systemically, with or withoutadded excipients. Actual methods for preparing parenterallyadministrable compositions will be known or apparent to those skilled inthe art and are described in more detail in such publications asRemington's Pharmaceutical Science, 15th ed., Mack Publishing Company,Easton, Pa. (1980).

It is recognized that polysialic acid derivatives and related compoundsdescribed herein (e.g., conjugates), when administered orally, should beprotected from digestion. This is typically accomplished either bycomplexing the polysialic acid derivative with a composition to renderit resistant to acidic and enzymatic hydrolysis or by packaging in anappropriately resistant carrier such as a liposome. Means of protectinga compound of interest from digestion are well known in the art.

In order to enhance serum half-life, the antigenic preparations that areinjected may also be encapsulated, introduced into the lumen ofliposomes, prepared as a colloid, or other conventional techniques maybe employed which provide an extended serum half-life of the peptides. Avariety of methods are available for preparing liposomes, as describedin, e.g., Szoka et al., Ann. Rev. Biophys. Bioeng. 9:467 (1980), U.S.Pat. Nos. 4,235,871, 4,501,728 and 4,837,028. The preparations may alsobe provided in controlled release or slow-release forms for release andadministration of the antigen preparations as a mixture or in serialfashion.

The compositions are administered to suitable subject, e.g., a subjectthat is at risk from acquiring a Neisserial disease or at risk ofdeveloping a cancer bearing a deNAc SA epitope (e.g., as present in aSEAM 3-reactive antigen) to prevent or at least partially arrest thedevelopment of disease and its complications. An amount adequate toaccomplish this is defined as a “therapeutically effective dose.”Amounts effective for therapeutic use will depend on, e.g., the antigencomposition, the manner of administration, and a variety ofsubject-specific parameters such as the weight and general state ofhealth of the subject, any or all of which may be modified according tothe judgment of the clinician.

Single or multiple doses of the antigen compositions may be administereddepending on the dosage and frequency required and tolerated by thepatient, and route of administration. In general, immunization isprovided to as to elicit an immune response in the subject, where thesuch immunization may be advantageous in that it does not elicitdetectable antibodies that significantly cross-react with polysialicacid in the subject (stated differently, elicits no clinically relevantautoantibody response directed against host sialic acid), and caninclude production of antibodies bactericidal for N. meningitidis aswell as for E. coli K1 and/or production of antibodies that inhibitcancer cell proliferation.

In particular embodiments, the antigen compositions described herein areadministered serially. First, an immunogenically effective dose of apolysialic acid derivative (which may be conjugated to a carrier, andmay be with or without excipients) is administered to a subject. Thefirst dose is generally administered in an amount effective to elicit animmune response (e.g., activation of B and/or T cells). Amounts for theinitial immunization generally range from about 0.001 mg to about 1.0 mgper 70 kilogram patient, more commonly from about 0.001 mg to about 0.2mg per 70 kilogram patient, usually about 0.005 mg to about 0.015 mg per70 kilogram patient. Dosages from 0.001 up to about 10 mg per patientper day may be used, particularly when the antigen is administered to asecluded site and not into the blood stream, such as into a body cavityor into a lumen of an organ. Substantially higher dosages (e.g. 10 to100 mg or more) are possible in oral, nasal, or topical administration.

After administration of the first antigen composition of polysialic acidderivative, a therapeutically effective dose of a second antigencomposition (e.g. polysialic acid derivative, optionally conjugated andwith or without excipients) is administered to the subject after thesubject has been immunologically primed by exposure to the first dose.The booster may be administered days, weeks or months after the initialimmunization, depending upon the patient's response and condition.

The presence of a desired immune response may be determined by knownmethods (e.g. by obtaining serum from the individual before and afterthe initial immunization, and demonstrating a change in the individual'simmune status, for example an immunoprecipitation assay, or an ELISA, ora bactericidal assay, or a Western blot, or flow cytometric assay, orthe like) and/or demonstrating that the magnitude of the immune responseto the second injection is higher than that of a control subjectimmunized for the first time with the composition used for the secondinjection (e.g. immunological priming). Immunologic priming and/or theexistence of an immune response to the first antigen composition mayalso be assumed by waiting for a period of time after the firstimmunization that, based on previous experience, is a sufficient timefor an immune response and/or priming to have taken place—e.g. 2, 4, 6,10 or 14 weeks. Boosting dosages of the second antigen composition aretypically from about 0.001 mg to about 1.0 mg of antigen, depending onthe nature of the immunogen and route of immunization.

In certain embodiments, a therapeutically effective dose of a thirdantigen composition prepared from is administered to the subject afterthe individual has been primed and/or mounted an immune response to thesecond antigen composition. The methods disclosed herein alsocontemplate administration of a fourth, fifth, sixth or greater boosterimmunization, using either a fourth, fifth or sixth antigen composition.

The subject may be immunologically naïve with respect to Neisseriameningitidis or E. coli K1 or a deNAc SA epitope-bearing cancer. Forimmunoprevention, the polysialic acid derivative can be administeredprior the first sign of disease symptoms, or at the first sign ofpossible or actual exposure to infection or disease (e.g., due toexposure or infection by Neisseria or E. coli K1).

Passive Immunization and Other Antibody-Based Therapies

In addition, antibodies generated against polysialic acid derivative orSEAM 3 using the methods described herein can be used to provide forpassive immunotherapy, e.g., to treat or prevent N.meningitidis-mediated or E. coli K1-mediated disease in mammaliansubjects. Particularly, the SEAM 3 or antibodies generated using thepolysialic acid derivative conjugates thereof according to the presentdisclosure can be provided in a pharmaceutical composition suitable foradministration to a subject, so as to provide for passive protection ofthe subject against N. meningitidis of E. coli K1 disease, or fortreatment of cancer.

More particularly, immunoprotective antibodies such as SEAM 3 thatrecognize Neisserial PS or E. coli K1 epitopes can be administered to asubject (e.g. a human patient) to induce passive immunity against aNeisserial disease, either to prevent infection or disease fromoccurring, or as a therapy to improve the clinical outcome in patientswith established disease (e.g. decreased complication rate such asshock, decreased mortality rate, or decreased morbidity, such asdeafness). Where the antibodies are administered to effect a cancertherapy, the antibodies can optionally have attached a drug fortargeting to the cancer cell to effect tumor killing or clearance, e.g.,a toxin (e.g., ricin), radionuclide, and the like).

Diagnostics

The polysialic acids derivatives disclosed herein may be used in variousdiagnostic settings. In particular, they may be used to increase theamount of a detectable antigen on the surface of a cancer cell forsecondary detection, or by use of conjugates of the derivativescomprising a detectable label. Also, to facilitate the identification ofa subject more amenable to therapy with the compositions of the presentdisclosure, antibodies such as SEAM 3 that are reactive with a deNAc SAepitope can be used to detect deNAc SA antigens in a biological sampleobtained from a subject having or suspected of having bacterialinfection or cancerous cells having a cell surface accessible deNAc SAepitope (e.g., a de-N-acetylated cell surface ganglioside orglycoconjugate) using anti-deNAc SA epitope antibodies inimmunodiagnostic techniques as described in (See U.S. Ser. No.11/645,255 and PCT Application No. US2006/048850; incorporated herein byreference). Such diagnostics can be useful to identify patients amenableto the therapies disclosed herein, and/or to monitor response totherapy. Further, such diagnostics can have antibodies that exhibitlittle or no detectable binding to host (e.g., mammalian, especiallyhuman) polysialic acid, thereby providing for decreased risk of falsepositive results. The diagnostics aspect of the present disclosure canalso be exploited for clinical trials and the like, as well asmanufacturing and release assays in the product of the compositions ofthe present disclosure.

Briefly, the antigen binding specificity of anti-deNAc SA epitopeantibodies can be exploited in this context, to facilitate detection ofdeNAc SA epitopes on a cancerous or bacterial cell in a sample withlittle or no detectable binding to host-derived PSA, thereby reducingthe incidence of false positive results. Such detection methods can beused in the context of diagnosis, identification of subject suitable topolysialic acid derivative-based therapy where the antibody specificallybinds an deNAc SA epitope and/or a SEAM 3-reactive antigen, monitoringof therapy (e.g., to follow response to therapy), and the like.

Suitable immunodiagnostic techniques include, but are not necessarilylimited to, both in vitro and in vivo (imaging) methods. Where themethods are in vitro, the biological sample can be any sample in which adeNAc SA antigen may be present, including but not limited to, bloodsamples (including whole blood, serum, etc.), tissues, whole cells(e.g., intact cells), and tissue or cell extracts. Assays can take awide variety of forms, such as competition, direct reaction, or sandwichtype assays. Exemplary assays include Western blots; agglutinationtests; enzyme-labeled and mediated immunoassays, such as ELISAs;biotin/avidin type assays; radioimmunoas says; immunoelectrophoresis;immunoprecipitation, and the like. The reactions generally includedetectable labels such as fluorescent, chemiluminescent, radioactive,enzymatic labels or dye molecules, or other methods for detecting theformation of a complex between antigen in the sample and the antibody orantibodies reacted therewith.

The assays can involve separation of unbound antibody in a liquid phasefrom a solid phase support to which antigen-antibody complexes arebound. Solid supports which can be used in the practice of the presentdisclosure include substrates such as nitrocellulose (e.g., in membraneor microtiter well form); polyvinylchloride (e.g., sheets or microtiterwells); polystyrene latex (e.g., beads or microtiter plates);polyvinylidine fluoride; diazotized paper; nylon membranes; activatedbeads, magnetically responsive beads, and the like.

Where a solid support is used, the solid support is usually firstreacted with a solid phase component (e.g., an anti-deNAc SA epitopeantibody) under suitable binding conditions such that the component issufficiently immobilized to the support. Sometimes, immobilization tothe support can be enhanced by first coupling the antibody to a proteinwith better binding properties, or that provides for immobilization ofthe antibody on the support with out significant loss of antibodybinding activity or specificity. Suitable coupling proteins include, butare not limited to, macromolecules such as serum albumins includingbovine serum albumin (BSA), keyhole limpet hemocyanin, immunoglobulinmolecules, thyroglobulin, ovalbumin, and other proteins well known tothose skilled in the art. Other molecules that can be used to bindantibodies the support include polysaccharides, polylactic acids,polyglycolic acids, polymeric amino acids, amino acid copolymers, andthe like, with the proviso that the molecule used to immobilize theantibody does not adversely impact the ability of the antibody tospecifically bind antigen. Such molecules and methods of coupling thesemolecules to the antigens, are well known to those of ordinary skill inthe art. See, e.g., Brinkley, M. A. Bioconjugate Chem. (1992) 3:2-13;Hashida et al., J. Appl. Biochem. (1984) 6:56-63; and Anjaneyulu andStaros, International J. of Peptide and Protein Res. (1987) 30:117-124.

After reacting the solid support with the solid phase component, anynon-immobilized solid-phase components are removed from the support bywashing, and the support-bound component is then contacted with abiological sample suspected of containing deNAc SA epitopes undersuitable binding conditions. After washing to remove any non-boundligand, a secondary binder moiety is added under suitable bindingconditions, wherein the secondary binder is capable of associatingselectively with the bound ligand. The presence or absence of thesecondary binder can then be detected using techniques well known in theart.

An ELISA method can be used, wherein the wells of a microtiter plate arecoated with anti-deNAc SA epitope antibody according to the presentdisclosure. A biological sample containing or suspected of containing adeNAc SA antigen (e.g., a tumor antigen having a deNAc SA epitope, suchas a de-N-acetylated ganglioside), is then added to the coated wells.After a period of incubation sufficient to allow antibody binding, theplate(s) can be washed to remove unbound moieties and a detectablylabeled secondary binding molecule added. The secondary binding moleculeis allowed to react with any captured antigen, the plate washed and thepresence or absence of the secondary binding molecule detected usingmethods well known in the art.

Where desired, the presence or absence of bound deNAc SA antigen from abiological sample can be readily detected using a secondary bindercomprising an antibody directed against the antibody ligands. Forexample, a number of anti-murine immunoglobulin (Ig) molecules are knownin the art, which can be readily conjugated to a detectable enzymelabel, such as horseradish peroxidase, alkaline phosphatase or urease,using methods known to those of skill in the art. An appropriate enzymesubstrate is then used to generate a detectable signal. In other relatedembodiments, competitive-type ELISA techniques can be practiced usingmethods known to those skilled in the art.

Assays can also be conducted in solution, such that the antibodies anddeNAc SA antigen form complexes under precipitating conditions. Forexample, the antibody can be attached to a solid phase particle (e.g.,an agarose bead or the like) using coupling techniques known in the art,such as by direct chemical or indirect coupling. The antibody-coatedparticle is then contacted under suitable binding conditions with abiological sample suspected of containing deNAc SA antigen to providefor formation of particle-antibody-deNAc SA antigen complex aggregateswhich can be precipitated and separated from the sample using washingand/or centrifugation. The reaction mixture can be analyzed to determinethe presence or absence of antibody-antigen complexes using any of anumber of standard methods, such as those immunodiagnostic methodsdescribed above.

The test sample used in the diagnostics assays can be any sample inwhich a deNAc SA antigen may be present, including but not limited to,blood samples (including whole blood, serum, etc.), tissues, whole cells(e.g., intact cells), and tissue or cell extracts containing cells(e.g., tissue, isolated cells, etc.), a cell lysate (i.e., a samplecontaining non-intact cells), where each type of sample can containelements of both types (e.g., a sample of cells can contain celllysates, and vice versa). In some embodiments, particularly as inembodiments involving detection of cancer cells, it may be desirable toconduct the assay using a sample from the subject to be diagnosed thatcontains intact, living cells. deNAc SA antigen detection can then beassessed on an extracellular surface of the cells, and can further beassessed during cell division.

Diagnostic assays can also be conducted in situ. For example, anti-deNAcSA epitope antibodies can be detectably labeled, administered to asubject suspected of having a cancer characterized by cell surfaceexpression of a deNAc SA epitope, and bound detectably labeled antibodydetected using imaging methods available in the art.

The diagnostic assays described herein can be used to determine whethera subject has a bacterial infection or cancer that is more or lessamenable to therapy using polysialic acid derivative-based therapy, aswell as monitor the progress of treatment in a subject. It also may beused to assess the course of other combination therapies (e.g., deNAc SAantigen vaccine and/or anti-deNAc SA antigen antibody therapy asdescribed in (U.S. Ser. No. 11/645,255 and PCT Application No.US2006/048850; incorporated herein by reference). Thus, the diagnosticassays can inform selection of therapy and treatment regimen by aclinician.

Where the methods are in vitro, the biological sample can be any samplein which a SEAM 3-reactive antigen may be present, including but notlimited to, blood samples (including whole blood, serum, etc.), tissues,whole cells (e.g., intact cells, i.e., cells that have not beensubjected to permeabilization), or cell lysates (e.g., as obtained fromtreatment of a tissue sample). For example, the assay can involvedetection of a SEAM 3-reactive antigen on cells in a histological tissuesample. For example, the tissue sample may be fixed (e.g., by formalintreatment) and may be provided embedded in a support (e.g., in paraffin)or frozen unfixed tissue.

The SEAM 3-reactive antigen can be detected by detection of specificbinding of an antibody, usually a monoclonal antibody (mAb), that hasthe antigen-binding specificity of SEAM 3. In this embodiment, the SEAM3-reactive antigen may be present on the cell surface at any stage ofthe cell cycle, including during cell division. Of note is that in someinstances, cancers that present a SEAM 3-reactive antigen during celldivision may present a lower or no detectable level of SEAM 3-reactiveantigen when the cell is quiescent (i.e., not undergoing cell division).However, as illustrated in the examples below, SEAM 3-reactive antigencan be detected in non-dividing cells by detecting SEAM 3-reactiveantigen in a permeabilized test cell. A test cancer cell that exhibits apattern of staining with a SEAM 3 antibody (or an antibody having theantigen binding specificity of SEAM 3) that is distinct from a patternof antibody staining in a normal cell is identified as a cancerous cellthat exhibits a SEAM 3-reactive antigen. Such cancers are thus amenableto therapy with an antibody that specifically binds the SEAM 3-reactiveantigen (e.g., the mAb SEAM 3).

The above-described assay reagents, including the antibodies generatedby immunization with a deNAc SA antigen according to the methodsdescribed in U.S. Ser. No. 11/645,255 and PCT Application No.US2006/048850, can be provided in kits, with suitable instructions andother necessary reagents, in order to conduct immunoassays as describedabove. The kit can also contain, depending on the particular immunoassayused, suitable labels and other packaged reagents and materials (i.e.wash buffers and the like). Standard immunoassays, such as thosedescribed above, can be conducted using these kits.

Kits & Systems

Also provided are kits and systems that find use in practicing themethods of the present disclosure, as described above. For example, kitsand systems for practicing the methods of the present disclosure mayinclude one or more pharmaceutical formulations that include polysialicacid derivative. As such, in certain embodiments the kits may include asingle pharmaceutical composition present as one or more unit dosages.In yet other embodiments, the kits may include two or more separatepharmaceutical compositions.

Thus the kits can include one or more of, depending upon the intendeduse of the kit, the compositions described herein, such as: a polysialicacid derivative and/or antibody specific thereto, cells suitable relatedfor assays or screening, an anti-deNAc SA epitope antibody, and thelike. Other optional components of the kit include: buffers, etc., foradministering a polysialic acid derivative and/or antibody specificthereto, and/or for performing a diagnostic assay. The variouscomponents of the kit may be present in separate containers or certaincompatible components may be pre-combined into a single container, asdesired.

In addition to the above components, the kits may further includeinstructions for practicing the methods disclosed herein. Theseinstructions may be present in the kits in a variety of forms, one ormore of which may be present in or on the kit. One form in which theseinstructions may be present is as printed information on a suitablemedium or substrate, e.g., a piece or pieces of paper on which theinformation is printed, in or on the packaging of the kit, in a packageinsert, etc. Yet another means would be a computer readable medium,e.g., diskette, CD, etc., on which the information has been recorded.Yet another means that may be present is a website address which may beused via the internet to access the information at a removed site. Anyconvenient means may be present in the kits.

In a specific embodiment, a kit is provided for use in treating a hostsuffering from a cellular proliferative disease condition. This kitincludes a pharmaceutical composition comprising an polysialic acidderivative, and instructions for the effective use of the pharmaceuticalcomposition in a method of treating a host suffering from a cancerouscondition by enhancing de-N-acetyl sialic acid antigen of a cancer cellso as to facilitate an immune response against the cancer cell and/orfacilitate binding of an anti-de-N-acetyl sialic acid antigen to thecancer cells, and/or by providing for administration of an immunogenicform of a polysialic acid derivative to elicit an anti-de-N-acetylsialic acid antigen immune response, e.g., to elicit antibodies thatbind a cancer cell bearing a deNAc SA epitope. Such instructions mayinclude not only the appropriate handling properties, dosing regimentand method of administration, and the like, but can further includeinstructions to optionally screen the subject for a de-N-acetylatedsialic acid (deNAc SA) epitope. This aspect can assist the practitionerof the kit in gauging the potential responsiveness of the subject totreatment with a polysialic acid derivative and/or antibody specificthereto, including timing and duration of treatment relative to the typeand growth stage of the cancer. Thus in another embodiment, the kit mayfurther include an antibody or other reagent for detecting ade-N-acetylated sialic acid (deNAc SA) epitope on an extracellularlyaccessible surface of a cancer cell, such as SEAM 3 (ATCC Deposit No.HB-12170). In another embodiment, the kit includes one or morepolysialic acid derivatives that comprise a conjugate with a detectablelabel, such as a fluorophore. Such polysialic acid derivatives can beuseful in labeling cancer cells either in vitro (e.g., as in a biopsy)or in vivo (e.g., as in in situ imaging methods), where the cancer cellsincorporate the detectably labeled polysialic acid derivative to as toprovide for an increase in a detectable signal in cancerous cells (e.g.,as compared to non-cancerous cells into which little or no detectablepolysialic acid derivative is incorporated).

In another specific embodiment, a kit is provided for use in immunizinga host at risk of, or having, a disease or disease symptom of infectionby a bacteria bearing a deNAc SA epitope, e.g., a deNAc SA epitope on abacterial polysaccharide capsule (e.g., Neisseria (e.g., N.meningitidis, especially Group B N. meningitidis), E. coli K1). This kitincludes a pharmaceutical composition comprising a polysialic acidderivative and/or antibody specific thereto, and instructions for theeffective use in immunization or treatment of a host having, or at riskof, bacterial infection. Such instructions may include not only theappropriate handling properties, dosing regiment and method ofadministration, and the like, but can further include instructions tooptionally screen the subject for a de-N-acetylated sialic acid (deNAcSA) epitope. This aspect assists the practitioner of the kit in gaugingthe potential responsiveness of the subject to immunization with apolysialic acid derivative and/or antibody specific thereto. Thus inanother embodiment, the kit may further include an antibody or otherreagent for detecting a de-N-acetylated sialic acid (deNAc SA) epitopeon an extracellularly accessible surface of a cancer cell, such as SEAM3 (ATCC Deposit No. HB-12170).

The term “system” as employed herein refers to a collection of anpolysialic acid derivative and/or antibody specific thereto and one ormore second therapeutic agents, present in single or disparatecompositions that are brought together for the purpose of practicing themethods disclosed herein. For example, separately obtained polysialicacid derivative and/or antibody specific thereto and chemotherapy dosageforms brought together and co-administered to a subject are a systemaccording to the present invention.

The following examples further illustrate the present invention andshould not be construed as in any way limiting its scope.

EXAMPLES

It is understood that the examples and embodiments described herein arefor illustrative purposes only and that various modifications or changesin light thereof will be suggested to persons skilled in the art and areto be included within the spirit and purview of this application andscope of the appended claims. All publications, patents, and patentapplications cited herein are hereby incorporated by reference in theirentirety for all purposes.

Preparation of a synthetic de-N-acetyl sialic acid antigen (poly alpha(2→8) N-acetyl neuraminic acid) that is enriched in non-reducing endde-N-acetyl residues and resistant to exoneuraminidase degradation isdescribed in Examples 1-3. Testing of the material against otherpolysialic acid materials not-enriched or resistant to exoneuraminidasedegradation, and their ability to be taken up and presented on the cellsurface without being substantially degraded following exogenousexposure to various cancer cells is described in Examples 4-5. Example 6describes the ability of the synthetic antigen to facilitate not onlybinding of antibody, but its uptake into the cell. Examples 7 and 8describe the preparation of N-propionyl PSA antigen and SEAM 3 inhibitorassay, respectively. Example 9 describes an exemplary method fordetermining N-acetyl sialic acid and de-N-acetyl sialic acid content inpolysialic acid (PSA) derivatives (and shorter chain length PSAderivatives referred to as oligosialic acid or oligosaccharide (OS)derivatives). Example 10 describes production of defined OS derivativescontaining de-N-acetyl sialic acid residues by time controlled alkalinede-N-acetylation. Example 11 describes the effect of OS produced inaccordance with Example 10 on the viability of Jurkat T-cell leukemiacells. Example 12 describes production of defined OS derivativesenriched for non-reducing end de-N-acetyl residues by time controlledde-N-acetylation and non-oxidizing acid hydrolysis of PSA materials.Example 13 describes the purification of OS derivatives produced inaccordance with Example 12 that are cytotoxic to Jurkat leukemia cells.

Example 1 De-N-Acetylation of Colominic Acid

Colominic acid (100 mg, Sigma-Aldrich Chemical Company, Saint Louis,Mo.) and 10 mg of sodium borohydride (Sigma-Aldrich) were dissolved in8.8 ml of water. A solution of 50% (weight/weight) of sodium hydroxide(1.2 ml) was added, the solution was mixed, placed in a glass hydrolysistube fitted with a Teflon closure (Pierce Chemical Company, Rockford,Ill.), and heated to 90° C. to 100° C. for 2 hrs. The solution wasallowed to cool to ambient temperature and 2M HCl was added to lower thepH of the solution to approximately 8. The solution was dialyzed (1 kDacutoff) twice in 4 L of water and lyophilized.

Example 2 Partial Re-N-Acetylation of De-N-Acetylated Colominic Acid

The lyophilized de-N-acetylated colominic acid (approximately 80 mg) wasresuspended in 5 ml of water and the pH adjusted to 8-9 with 2M NaOH.Acetic anhydride (Sigma-Aldrich) was added in five aliquots of 0.1 mlover a period of several hours with stirring. The pH of the solution wasmonitored with a pH meter and 2M NaOH was added as necessary to maintainthe pH between 8 and 9. At the completion of the reaction, the solutionwas dialyzed and lyophilized as before. The re-N-acetylated colominicacid typically contains 10% to 30% de-N-acetylated residues asdetermined by resorcinol assay (see Example 9).

Example 3 Enrichment for PSA Containing Non-Reducing End De-N-AcetylResidues

The PSA material of Example 2 was enriched for non-reducing endde-N-acetyl residues by treatment with the exoneuraminidase SIALIDASE A™(Prozyme, San Leandro, Calif.). Lyophilized re-N-acetylated colominicacid powder (50 mg) from Example 2 was resuspended in 2.5 ml of 50 mMsodium phosphate buffer, pH 7. SIALIDASE A™ (10 μl, 1 U/ml, Prozyme) wasadded and the solution was transferred to dialysis tubing (1 kDa cutoff)then placed in 1 L of 50 mM sodium phosphate buffer, pH 7 at 37° C. for3-4 days. N-acetyl neuraminic acid released by the enzyme passes throughthe dialysis membrane, whereas enzyme and PSA terminating at thenon-reducing end in a de-N-acetyl residue is retained.

Alternatively, the PSA material was resuspended in 5.0 ml of 50 mMsodium acetate buffer, pH 6.5. Sialidase A (25 ul, 1 U/ml) was added andthe reaction placed at 37° C. for 2 days. Afterwards, 0.1 M NaOH wasadded for 1 hr at room temperature to terminate the reaction, thenneutralized with glacial AcOH. N-acetyl neuraminic acid released by theenzyme was removed by dialysis (1 kDa cutoff) against 4 L water, twotimes.

Example 4 Increasing Expression of Seam 3-Reactive Antigens in CancerCells

The effect of exogenous PSA derivatives from Example 3 was tested on theexpression of PSA antigens that contained neuraminic acid (that is,de-N-acetyl neuraminic acid residues in PSA). CHP-134 neuroblastoma,Jurkat T-cell leukemia, and SK-MEL 28 melanoma cells were examined forbinding to SEAM 3 exposed to the PSA derivatives by flow cytometry afterculturing the cells in the presence of the derivatives. SEAM 3specifically recognizes PSA containing neuraminic acid residues (U.S.Ser. No. 11/645,255 and PCT Application No. US2006/048850; incorporatedherein by reference).

Cells (approximately 10⁵ per well) were plated onto a flat bottom96-well tissue culture plate (Nunc, Thermo-Fisher) and incubated withgrowth medium supplemented with 10 mM (based on a residue mass of 290Da) colominic acid (i.e. PSA capsular polysaccharide from E. coli K1bacteria, Sigma-Aldrich), re-N-acetylated colominic acid (“ReAc”) thathad not been treated with SIALIDASE A™, and SIALIDASE A™-treatedre-N-acetylated PSA (“ReAcSia”) for 24 hrs before measuring binding.Prior to adding to the cell cultures, the colominic acid derivativeswere heated to 56° C. for 1 hr to inactivate any contaminatingmicroorganisms.

After incubation, cells were detached from the plate (Jurkat cells arenon-adherent) by either trypsin (SK-MEL-28) or Cell Dispersal Reagent(CDR, Guava Technologies, Hayward, Calif.) (CHP-134) before beingcollected into a 96-round bottom plate (Falcon), spun at 1000×g for 5minutes and fixed with ice-cold 1% (v/v) formaldehyde. After 20 minutescells were pelleted by centrifugation (above) and incubated in ablocking solution of 3% (v/v) goat serum for 1 hour. After blocking, theprimary antibodies were added and incubated overnight at 4° C. The cellswere washed twice by pelleting and resuspension in ice-cold PBS.Secondary antibody (FITC-conjugated goat anti-mouse IgG (Fab)₂, JacksonImmunoresearch, West Grove, Pa.) was incubated with the cells for atleast 1 hour at 4° C. in the dark. After another series of spins andwashes (3 times) binding was analyzed by a Guava EastCyte flow cytometer(Guava Technologies). Control samples were treated with an isotypematched irrelevant antibody (Southern Biotech, Birmingham, Ala.), whichwere used to create baseline fluorescence, or positive control mAbs thatare reactive with antigens specifically expressed by the cells (i.e.anti-GD3 mAb R24 (MEL-1 from Axxora LLC, San Diego, Calif.) for SK-MEL28 cells.

As shown in FIGS. 1-4, SEAM 3 binds to the surface of all three celllines. The percent of cells positive for SEAM 3 binding increases whenthe cells were incubated with either re-N-acetylated colominic acid(“ReAc”) or SIALIDASE A™-treated re-N-acetylated PSA (“ReAcSia”)compared to no derivative (None) or colominic acid (Col) as shown inFIG. 4. In fact, incubation with colominic acid decreases the percentageof cells that are positive for SEAM 3 binding (FIG. 4 upper panels).Importantly, the fluorescence of cells incubated with sialidase-treatedre-N-acetylated colominic acid (ReAcSia) increases 10- to 30-fold (FIG.4 lower panels) compared to no derivative, colominic acid, orre-N-acetylated colominic acid (ReAc) demonstrating that the amount ofSEAM 3-reactive PSA containing neuraminic acid on the cell surface isgreatly increase by providing the derivative exogenously.

Example 5 Confocal Microscopy

To show that the exogenously supplemented SIALIDASE A™-treatedre-N-acetylated PSA (“ReAcSia”) is taken up by cells and incorporatedinto glycoconjugate, binding of SEAM 3 to SK-MEL 28 cells incubated withcolominic acid or ReAcSia prepared as described in Example 3 wasanalyzed by confocal microscopy. SK-Mel-28 cells (approximately 10⁵cells) were cultured on multi-well microscope slides that had beentreated with ploy-L-lysine (Nunc). After an overnight incubation withthe indicated colominic acid derivative (2.5 mg/ml), cells were gentlywashed with PBS buffer and fixed with ice-cold 1% (v/v) formaldehyde.After 20 minutes cells were washed with PBS before blocking non-specificbinding with a solution of 5% goat serum for 1 hour. To observe thepresence of SEAM 3-reactive antigen that is present inside the cells,the cells were treated Triton X-100 (0.5% weight/volume; Sigma) in 5%goat serum for 1 hour. After removing the Triton by pelleting the cellsand washing, he primary antibodies were added and incubated forovernight at 4° C. Cells were gently washed by a series (at least twice)with ice-cold PBS before isotype-specific secondary antibody (producedin goat) conjugated with either Alexa Fluor 488, Alexa Fluor 546, orAlexa Fluor 633 was applied for at least 1 hour at 4° C. in the dark(all secondary antibodies conjugated to fluorophores were obtained fromInvitrogen, Carlsbad, Calif.). After another series of gentle washes, ahardening mounting medium containing DAPI (Vectrashield™, VectorLaboratories, Burlingame, Calif.) was applied.

Confocal images were obtained using a Zeiss Meta510 CLSM microscope atthe Biological Imaging Facility, University of California, Berkeley,Calif. and were analyzed using ImageJ Software (NIH). Control antibodiesand secondary antibodies applied alone were routinely used to assessbackground fluorescence. The positive control mAb that is specific forthe ganglioside GD3, R24 was positive for binding to SK-MEL-28 melanomacells (data not shown).

FIG. 5 shows the fluorescence on the cell surface (red staining in thegray scale figure represented by light gray surrounding a dark nucleus)resulting from SEAM 3 binding to SK-MEL-28 melanoma cells as measured byconfocal microscopy. The fluorescence is uniform over the cell surfaceand all cells in the visual field show bright fluorescence associatedwith SEAM 3 binding. FIG. 5, Panel A shows cells incubated withcolominic acid alone, FIG. 5, Panel B shows the large increase in SEAM 3binding when cells were incubated with re-N-acetylated colominic acidtreated with sialidase (“ReAcSia”). FIG. 5, Panels C and 5D show thepresence of intracellular SEAM 3-reactive antigens in cells incubatedwith colominic acid or ReAcSia, respectively, made permeable to the mAbby treatment with the detergent Triton X-100. The increased presence ofSEAM 3-reactive antigens inside the cells revealed by confocalmicroscopy shows that contacting the cells with the ReAcSia derivativeresults in cellular uptake of the derivative and incorporation intoglycoconjugates present in intracellular vesicles, the golgi complex,and the nuclear membrane.

Example 6 Measuring Monoclonal Antibody Uptake—Internalization of Seam 3by SK-MEL 28 Cells

The purpose of this experiment was to determine whether SEAM 3 bound toantigens expressed on the cell surface results in SEAM 3 being taken upby the cells through endocytosis. SK-MEL 28 cells were cultured on 6well tissue culture plates (Nunc) as described above in Example 5. SEAM3 (1 μg/ml), anti-GD3 mAb R24 (10 μg/ml), and irrelevant mouse IgG2b andIgG3 isotype control mAbs (10 μg/ml, Southern Biotech, Birmingham, Ala.)were incubated with the cells for 48 hrs. The adherent cells were thengently washed 3× with PBS buffer and finally suspended in RIPA celllysis and extraction buffer (250 μl, Pierce Chemical Company, Rockford,Ill.) using the plunger from a 1 ml plastic syringe to mix the cells andbuffer. The cell/RIPA suspension was mixed with an equal volume of2×SDS-PAGE sample buffer, boiled for 5 min and the proteins wereseparated on a 4% to 15% SDS-PAGE gradient gel (Bio-Rad, Richmond,Calif.).

The separated proteins were transferred to a nitrocellulose membrane forWestern blot using a Bio-Rad semi-dry transfer apparatus. After blockingthe membrane for 1 hour with 5% non-fat dry milk in PBS buffer,HRP-conjugated rabbit anti-mouse IgG, A, M secondary antibody (Zymed,South San Francisco, Calif.) was added in the same PBS/5% milk blockingbuffer. The membrane was washed and developed with Western Lightingchemiluminescence reagents (PerkinElmer, Waltham, Mass.). The region ofthe gel having an apparent molecule mass range of about 15 kDa to about35 kDa where the IgG light chain is located is shown in FIG. 6.

The Western blot shows that there was either a small amount (IgG2b) orno (IgG3) uptake of the negative control irrelevant mAbs. In contrast,endocytosis of R24, which has been shown to be internalized by SK-MEL 28cells (Iglesia-Bartolome et al, FEBS J, 2006, 273:1744) and especiallySEAM 3 was greatly increased. Thus, SEAM 3 binding to antigens expressedon the surface of SK-MEL 28 cells facilitate entry of the mAb into cellsand provide a means of delivering cytotoxic drugs and toxins attached tothe mAb.

Example 7 Preparation of Dodecylamine N-Propionyl Polysialic Acid (NPrPSA)

deNAc PSA (50 mg) prepared as described in Example 1, was suspended inwater (5 ml) and the pH adjusted to 8-9 with 2M NaOH. Propionicanhydride (Sigma-Aldrich) was added to the stirred solution in 5 0.1 mlaliquots over a period of 1 hr. The pH was maintained between 8 and 9 byadding 2 M NaOH. The reaction mixture was dialyzed in water andlyophilized as described above.

A solution of NPr PSA (10 mg/ml) was oxidized by with 1 mM sodiumperiodate (Sigma-Aldrich) in sodium acetate buffer, pH 6.5 for 30minutes at ambient temperature in the dark. Excess periodate wasdestroyed by adding a solution of ethylene glycol (Sigma-Aldrich) inwater to a final concentration of 1% (volume/volume) and incubating thesolution for an additional 30 minutes. The solution was dialyzed inwater and lyophilized.

Twenty (20) mg of oxidized NPr PSA prepared as described above wascombined in water (5 ml) with 5 μl of dodecylamine (Thermo-Fisher). ThepH was adjusted to 8 with 2M HCl and the mixture stirred for 3 hrs.Sodium cyanoborohydride (5 mg, Sigma-Aldrich) was added and the mixturewas stirred at ambient temperature for 24 hours then dialyzed in waterfor 3 to 5 days to remove excess dodecylamine. The dodecylamine NPrderivatives (˜1 mg/ml in PBS buffer) was stored at 4° C.

Example 8 Seam 3 Inhibitor Assay

ELISA plates for testing inhibitors of SEAM 3 binding were prepared bydiluting a selected dodecylamine NPr derivative of Example 7 above 1:200in PBS buffer and adding 100 μl per well of a 96 well microtiter plate(Immulon II HB, Dynatech, Chantilly, Va.). The plates were storedovernight at 4° C. before use in assays. The plates were washed with PBSbuffer (5×) and blocked with PBS buffer containing 1% (weight/volume) ofbovine serum albumin (Sigma; blocking buffer) for 1 hour at ambienttemperature. The PSA and OS derivatives were diluted in blocking bufferon the plate then SEAM 3 was added in blocking buffer (100 μl total perwell). After incubating the plate overnight at 4° C., the plates werewashed with PBS buffer (5×) and rabbit anti-mouse-alkaline phosphataseconjugate antibody (Zymed, South San Francisco, Calif.) diluted inblocking buffer was added. After incubating an additional hour, theplates were washed (5×) with PBS buffer and the bound antibody wasdetected by adding p-nitrophenyl phosphate substrate (Sigma-Aldrich) in50 mM sodium carbonate buffer, pH 9, containing 1 mM MgCl₂. Theabsorbance at 405 nm after 60 minutes incubation at ambient temperaturewas measured using a BioRad Model 550 microtiter plate reader (Richmond,Calif.).

Example 9 Determination of N-Acetyl and De-N-Acetyl Sialic Acid Contentin PSA and OS

The concentration of sialic acid and de-N-acetyl sialic acid in PSA orOS derivative stock solutions or column fractions was determined by theSvennerholm resorcinol reaction (Svennerholm, L. (1957) Biochim.Biophys. Acta 24:604) modified as follows. Resorcinol working reagentwas prepared by combining 9.75 ml of water, 0.25 ml of 0.1 M CuSO4.5H2O,10 ml of 20 milligram per ml solution of resorcinol in water, and 80 mlof concentrated HCl. The resorcinol working reagent (100 μl) wascombined with the sialic acid or de-N-acetyl sialic acid sample solution(up to 50 micrograms of sialic acid) or standard stock solution in water(100 μl) in a polypropylene deep well (2 ml) microtiter plate. The platewas sealed with a plate cover and heated in a boiling water bath for 30minutes. After cooling to ambient temperature, isoamyl alcohol (200 μl)was added and mixed using a pipette. The phases were allowed to separateand the upper isoamyl alcohol layer was removed to a clean microtiterplate. 100 μl of the isoamyl alcohol extract and the lower aqueoussolution were transferred separately to a polystyrene microtiter plateand the absorbance at 495 nm and 580 nm was measured.

The amount of N-acetyl sialic acid was determined from the absorbance ofthe isoamyl alcohol fraction at 585 nm and the amount of de-N-acetylsialic acid was determined from the absorbance of the aqueous fractionat 495 nm in comparison to a standard curve for each. The N-acetylsialic acid standard was N-acetyl neuraminic acid (Sigma) and thede-N-acetyl sialic acid standard was prepared as described in Example 1except that the alkaline hydrolysis reaction was 6 hours instead of 2hours. The amount of de-N-acetyl sialic acid was corrected for theamount of de-N-acetylation that occurs during the acid hydrolysis stepof the assay by measuring the amount of de-N-acetylation that occurs inthe sialic acid standard.

Example 10 Production of Os Derivatives by Time-ControlledDe-N-Acetylation

Synthesis of a mixture of PSA and OS derivatives enriched at thenon-reducing end for de-N-acetyl sialic acid residues is described inExample 3 and employs an enzymatic step. The chemical synthesis methoddescribed below does not require the use of enzymes, generates productscontaining few side products, and facilitates the purification ofdefined OS derivatives.

Colominic acid (100 mg) was combined with 10 mg of sodium borohydride in2M sodium hydroxide and heated to 90° C. to 100° C. in a glasshydrolysis tube as described in Example 1. Aliquots of 1 ml were removedfor analysis by high performance anion exchange chromatography withpulsed ampermetric detection (HPAC-PAD) using a CarboPac PA200 column(column, GP40 pump and ED40 electrochemical detector were from Dionex,Sunnyvale, Calif.) at T=0, 1, 2, and 6 hrs. The column was eluted with agradient of 93% buffer A (0.1 M sodium hydroxide) 7% buffer B (0.1 Msodium hydroxide containing 1 sodium acetate) to 0% buffer A and 100%buffer B over 40 minutes at a flow rate of 0.5 ml/minute. FIG. 7 showsHPAC-PAD chromatograms of the reaction mixture for each time point (1:t=0; 2: t=1 hr; 3: t=2 hrs; 4: t=6 hrs). Smaller oligosaccharides eluteearly and longer polysaccharides later. Each oligomer appears as adoublet at T=0 (chromatogram 1) since the sodium borohydride reductionof the C2 ketone produces two enantiomers. The progress ofde-N-acetylation with increasing time is indicated by the appearance ofmultiple peaks for each oligomer after 1 hour which eventually convertto a single peak for each oligomer with complete de-N-acetylation. After2 hrs, an increasing number of degradation products are produced thatappear as peaks between oligomer peaks.

To determine the optimal time for alkaline de-N-acetylation, theoligosaccharides in each aliquot were tested for their ability toincrease binding of SEAM 3 to Jurkat cells using the flow cytometricbinding assay described in Example 4. Before use in the binding assay,the pH of the aliquots was adjusted to 8 with 2M HCl, they were dialyzedin water, lyophilized and solutions (2.5 mg/ml) were sterilized byheating to 56° C. as described above. FIG. 8, Panel A is a bar graphshowing the mean fluorescence of Jurkat cells resulting from SEAM 3binding detected with a fluorescently labeled secondary antibody. Basedon the data presented in FIG. 8, Panel A, the optimal time forde-N-acetylation is 1 hr or less. The same experiment was repeated withaliquots sampled after hydrolysis for 10, 20, 40, and 60 minutes andwere tested for the ability to increase SEAM 3 binding (Example 4). Asshown in FIG. 8, Panel B, de-N-acetylation for 40 minutes producedderivatives that are most active in increasing SEAM 3 binding. This 40minute de-N-acetylation procedure typically generates 25%-60%de-N-acetylated residues for polysialic acid containing materials (e.g.,35% for colominic acid (NmB PSA) and 56% for NmC PSA) as determined byresorcinol assay Example 9)).

Example 11 Effect of Os Derivatives Produced by Time-ControlledDe-N-Acetylation on the Viability of Jurkat T-Cell Leukemia Cells

The effect of contacting the partially de-N-acetylated colominic acidderivatives (40 min deNAc col) prepared as described in Example 10 onthe viability of human T-cell leukemia Jurkat cell lines in culture wasmeasured using a cell viability assay. The 40 min deNAc col stocksolution in water was first heated to 56° C. for 1 hour sterilize thesolution. This is necessary since the 40 min deNAc col forms highmolecular mass aggregates that do not pass through a 0.22μ filter and,thus, the stock solutions in water can not be sterilized by filtration.Jurkat cells (2×10⁵ cells/ml) were incubated with several dilutions ofthe derivatives as indicated in FIG. 9 for 40 hours in round-bottom96-well plates (Falcon), 200 μl/well. Plates were then spun at 1,000×gfor 5 minutes. The cells were resuspended in Guava ViaCount reagent andread on a Guava EasyCyte flow cytometer, using the Guava ViaCount assay(all from Guava Technologies).

As shown in FIG. 9, the 40 min deNAc col derivatives reduce theviability of Jurkat cells. The viability curve has an extremeconcentration dependence, which is indicative of a highly cooperativeprocess, for example, the cooperative assembly of high molecular weightcomplexes.

Similar results were obtained for OS derivatives made from N.meningitidis Serogroup C capsular polysaccharide homopolymer composed ofN-acetyl neuraminic acid bearing C7-O-acetyl and C8-O-acetyl residueslinked by an α(2→9) glycosidic bond.

Example 12 Production of OS Derivatives Enriched for Non-Reducing EndDe-N-Acetyl Sialic Acid Residues by Non-Oxidizing Acid Hydrolysis

To produce smaller OS derivatives that are enriched for de-N-acetylsialic acid at the non-reducing end, the 40 min alkalinede-N-acetylation (process described in Example 10) was followed bynon-oxidizing acid hydrolysis in 0.1 M sodium acetate buffer, pH 5.5 for18 hrs in a hydrolysis tube (Pierce) in which dissolved gasses had beenevacuated by alternately freezing and thawing the solution under vacuum.Removal of dissolved gasses from the solution was found to be essentialto minimize oxidative damage to the polysaccharide that can occur in thepresence of strong acid or high concentrations (10%) of acetic acid.After cooling to ambient temperature, the pH was increased to 8-9 with2M NaOH. The solution was dialyzed in water and lyophilized as describedabove. The resulting material is enriched for Neu residues at thenon-reducing end and is substantially undamaged by oxidization

Example 13 Purification of Defined OS Derivative that is Cytotoxic toJurkat Leukemia Cells

OS (prepared by 40 min alkaline de-N-acetylation followed bynon-oxidizing acid hydrolysis in 0.1 M sodium acetate buffer, pH 5.5 for18 hrs as described in Example 12) were separated by ion exchangechromatography (AEC) on an Äkta™ FPLC fitted with a 5 ml HiTrap Q FF™anion exchange column (GE Healthcare Bio-Sciences Corp., Piscataway,N.J.). 20 mg of OS were diluted in 25 ml of 20 mM Bis-Tris buffer(Sigma-Aldrich), pH 7 and injected onto the column. OS were eluted (5ml/minute) from the column with a 0M to 0.25M gradient of sodiumchloride in 20 mM Bis-Tris buffer over a period of 30 min. Fractions (1ml) were collected in a deep well microtiter plate (Thermo-Fisher) inalternating forward and backward rows. The gradient and elution profileare shown in FIG. 10. The ability of each fraction to inhibit binding ofSEAM 3 to NPr PSA-dodecylamine (as prepared in Example 7) was determinedby inhibition ELISA (as described in Example 8). Also, a portion of eachfraction was analyzed by HPAC-PAD (as described in Example 10). FIG. 11shows the HPAC-PAD chromatograms of several fractions from the AECcolumn. Chromatogram 1 is the unpurified 40 min deNAc col preparation.Notice in particular in chromatogram 2 how a nearly pure dimer ispresent in fraction B9 while another dimer (chromatogram 3 in FIG. 11)in later fraction C2 elutes from the PA20 column earlier than the dimerfrom fraction B9 shown in chromatogram 2. The dimer in chromatogram 3 isN-acetylated on both residues, thus it elutes with a higherconcentration of salt from the AEC column. The example illustrates howAEC chromatography can be used to separate oligosaccharides containingdifferent amounts of Neu residues and how the oligosaccharidederivatives can be identified by HPAC-PAD.

Fractions containing a narrow size range of oligomers were pooled, asindicted by the letters above delineated peaks in FIG. 10, dialyzed inwater and lyophilized. Some of the individual fraction pools were thentested for their ability to decrease the viability of Jurkat cells asdescribed in Example 11 and the amount of N-acetyl and de-N-acetylsialic acid (Neu) was determined by resorcinol assay (Example 9). Thedata is summarized in Table 1.

TABLE 1 Pooled Percent Percent decrease in fraction Neu Jurkat cellviability A 36 25 B 17 15 C 19  9 F 14 28 G 32  8

The data presented in Table 1 shows that fractions containing thesmallest Neu-containing OS (for example pool A dp=2-5) have as muchcytotoxic activity as fractions containing the largest OS (pool F). Allassays were done with 2.5 mg/ml (sometimes expressed as 10 mM based on aresidue molecular mass of 250 g/ml)

The above results demonstrate that PSA and OS derivatives enriched forde-N-acetyl sialic acid at the non-reducing end were readily taken up bycancer cells, increased the number of cells positive for binding to SEAM3, and increased the amount of antibody bound to the cells. Thederivatives were also found capable of reducing viability of cancercells expressing SEAM 3-reactive antigen upon exposure andinternalization of antibodies directed against the antigen, and werecytotoxic to cancer cells at higher concentrations even in the absenceof antibody. High molecular weight complexes/aggregates of thederivatives were found to be particularly active.

In addition, methods have been described for producing, purifying, andcharacterizing defined Neu-containing OS derivatives that can be used toincrease expression of Neu-containing sialic acid antigens in cancercells. Small, substantially unoxidized and purified OS derivativeshaving a degree of polymerization of about 2-5, particularly about 2-4,and a non-reducing end de-N-acetyl sialic acid residue were found toexhibit as much activity as longer OS derivatives (dp=5+), indicatingthe smallest OS derivatives bearing a non-reducing end de-N-acetylsialic acid residue contain the minimal features necessary for effectiveactivity.

It is evident from the above results and discussion that the PSA and OSderivatives may be used alone, as conjugates, or to increase theeffectiveness of immunotherapy with SEAM 3, or other antibodies havingsimilar antigenic specificities, as well as the uptake of antibodiesthat have been modified with cytotoxic drugs, toxins, or radionuclides,particularly as applied to increase a de-N-acetyl epitope of a cell, andspecifically as applied to cancer therapy.

Although the foregoing invention has been described in some detail byway of illustration and example for purposes of clarity ofunderstanding, it is readily apparent to those of ordinary skill in theart in light of the teachings of this invention that certain changes andmodifications may be made thereto without departing from the spirit orscope of the appended claims.

What is claimed is:
 1. A method of increasing a de-N-acetylated antigenof a cancer cell, said method comprising: contacting a cancer cellhaving a de-N-acetyl sialic acid antigen with an effective amount of acomposition comprising a polysialic acid derivative to increase theamount of the de-N-acetyl sialic acid antigen of said cell, wherein saidpolysialic acid derivative is substantially unoxidized and purified andcomprises (i) a mixture of N-acetyl sialic acid and de-N-acetyl sialicacid residues, and (ii) a non-reducing end de-N-acetyl sialic acidresidue that is resistant to degradation by exoneuraminidase.
 2. Themethod of claim 1, wherein said cancer cell is a neuroblastoma cell, aleukemia cell, or a melanoma cell.
 3. The method of claim 1, whereinsaid cell is in a subject, and said contacting comprises administeringto said subject an effective amount of said composition.
 4. The methodof claim 3, wherein said administering is by infusion or by localinjection.
 5. The method of claim 3, wherein said administering is priorto surgical intervention to remove cancerous cells.
 6. The method ofclaim 3, wherein said administering is at the time of or after surgicalintervention to remove cancerous cells.
 7. The method of claim 3,further comprising: administering at least one of an immunotherapy, acancer chemotherapy or a radiation therapy to the subject.
 8. A methodof facilitating binding of an antibody to a cell having a de-N-acetylsialic acid antigen, said method comprising: contacting a cell having ade-N-acetyl sialic acid antigen with an effective amount of acomposition comprising a polysialic acid derivative so as to increasethe amount of said antigen on said cell, wherein said polysialic acidderivative is substantially unoxidized and purified and comprises (i) amixture of N-acetyl sialic acid and de-N-acetyl sialic acid residues,and (ii) a non-reducing end de-N-acetyl sialic acid residue that isresistant to degradation by exoneuraminidase; and contacting said cellwith an antibody specific for said antigen to facilitate binding of saidantibody to said cell.
 9. The method of claim 8, wherein binding of saidantibody to said cell is cytotoxic to the cell.
 10. The method of claim8, wherein said antibody comprises a conjugate.
 11. The method of claim10, wherein said conjugate comprises a detectable label or a cytotoxicdrug.
 12. The method of claim 8, wherein said cell is a cancer cell. 13.A method of reducing the viability of a cancer cell, said methodcomprising: contacting a cancer cell having a de-N-acetyl sialic acidantigen with an effective amount of a composition comprising apolysialic acid derivative so as to reduce the viability of said cell,wherein said polysialic acid derivative has a reducing end and anon-reducing end, and wherein said polysialic acid derivative is asubstantially unoxidized and purified oligosaccharide comprising (i) amixture of N-acetyl sialic acid and de-N-acetyl sialic acid residues,and (ii) a de-N-acetyl sialic acid residue at said non-reducing end thatis resistant to degradation by exoneuraminidase.
 14. The method of claim13, wherein said cancer cell is a neuroblastoma cell, a leukemia cell,or a melanoma cell.
 15. The method of claim 13, wherein said polysialicderivative comprises at least one dimer of de-N-acetyl sialic acid andN-acetyl sialic acid linked through a glycosidic bond selected fromα(2→8) and α(2→9).
 16. The method of claim 15, wherein said polysialicderivative has a degree of polymerization of about 2-10.
 17. The methodof claim 13, wherein said mixture comprises de-N-acetyl sialic residuesin an amount of about 10%-60%.
 18. The method of claim 13, wherein saidpolysialic acid derivative comprises a conjugate.
 19. The method ofclaim 13, wherein said cell is in a subject, and said contactingcomprises administering to said subject an effective amount of saidcomposition.